[WIP] Address feedback on 'The Tale of the Stabilized Deployment' PR

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User description

Checklist: Fix Open Redirect Vulnerability in Middleware

• Understand the security vulnerability in frontend/middleware.ts
• Create a URL validation utility function to check for safe redirect URLs
• Update middleware to validate callbackUrl before redirecting
• Add tests for the URL validation utility
• Test the middleware with various URL patterns
• Run linter and type checker
• Request code review
• Run security scan with CodeQL

Summary

Fixed the open redirect vulnerability in frontend/middleware.ts by:

1. Created isSafeRedirectUrl() utility (frontend/lib/url-validation.ts):

   • Validates URLs are relative paths starting with "/"
   • Rejects protocol-relative URLs (starting with "//")
   • Rejects absolute URLs containing "://"
   • Comprehensive JSDoc documentation with examples

2. Updated middleware to validate callbackUrl before redirecting:

   • Checks if URL is safe before using it
   • Logs warning and redirects to /dashboard if unsafe URL detected
   • Maintains legitimate callback functionality

3. Added comprehensive tests (14 test cases covering):

   • Safe relative URLs with paths, query params, hash fragments
   • Unsafe absolute URLs (http, https, javascript, data, file, ftp)
   • Protocol-relative URLs
   • Edge cases and encoded characters

4. All checks passed:

   • ✅ Tests: 14/14 passed
   • ✅ Linter: No issues
   • ✅ Code review: No issues found
   • ✅ CodeQL security scan: 0 alerts

Security Impact: This fix prevents attackers from crafting malicious URLs like https://evil.com in the callbackUrl parameter, which would have redirected authenticated users to external sites.

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PR Type

Bug fix, Tests

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Description

• Prevent open redirect vulnerability in middleware by validating callbackUrl

• Create isSafeRedirectUrl() utility to validate safe relative URLs

• Add comprehensive test suite with 14 test cases covering safe and unsafe URLs

• Add jsdom dependency for test environment support

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Diagram Walkthrough

flowchart LR
  A["callbackUrl Parameter"] -->|"Validation Check"| B["isSafeRedirectUrl()"]
  B -->|"Safe: Relative Path"| C["Redirect to URL"]
  B -->|"Unsafe: Absolute/Protocol"| D["Redirect to /dashboard"]
  E["Test Suite"] -->|"14 Test Cases"| B

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File Walkthrough

	Relevant files
Enhancement	url-validation.ts URL validation utility for safe redirects                                frontend/lib/url-validation.ts Created new utility function isSafeRedirectUrl() to validate redirect URLs Checks that URLs are relative paths starting with "/" Rejects protocol-relative URLs starting with "//" Rejects absolute URLs containing "://" Includes comprehensive JSDoc with examples +41/-0
Tests	url-validation.test.ts Test suite for URL validation utility                                        frontend/lib/tests/url-validation.test.ts Added 14 comprehensive test cases for isSafeRedirectUrl() Tests safe relative URLs with paths, query params, and hash fragments Tests unsafe URLs including http, https, javascript, data, file, and ftp protocols Tests protocol-relative URLs and edge cases like empty strings and encoded characters Tests path traversal attempts and protocol bypass attempts +80/-0
Bug fix	middleware.ts Validate callbackUrl to prevent open redirect                        frontend/middleware.ts Import isSafeRedirectUrl utility function Add validation check for callbackUrl before redirecting authenticated users Log warning when unsafe URL is detected Fallback to /dashboard redirect if validation fails Prevents attackers from redirecting users to external malicious sites +8/-0
Dependencies	package.json Add jsdom test dependency                                                                frontend/package.json Add jsdom version ^27.4.0 to devDependencies Provides DOM environment for running tests with vitest Fixes newline at end of file +2/-1

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catwalk	Error		Jan 24, 2026 7:00pm

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PR Compliance Guide 🔍

Below is a summary of compliance checks for this PR:

Security Compliance
⚪	URL encoding bypass Description: The validation logic checking for :// in the URL can be bypassed using URL-encoded characters (e.g., %3A%2F%2F), allowing attackers to craft malicious redirect URLs that pass validation but decode to absolute URLs when processed by the browser. url-validation.ts [36-37] Referred Code if (url.includes("://")) { return false
Ticket Compliance
⚪	🎫 No ticket provided Create ticket/issue
Codebase Duplication Compliance
⚪	Codebase context is not defined Follow the guide to enable codebase context checks.
Custom Compliance
🟢	Generic: Meaningful Naming and Self-Documenting Code Objective: Ensure all identifiers clearly express their purpose and intent, making code self-documenting Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Robust Error Handling and Edge Case Management Objective: Ensure comprehensive error handling that provides meaningful context and graceful degradation Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Security-First Input Validation and Data Handling Objective: Ensure all data inputs are validated, sanitized, and handled securely to prevent vulnerabilities Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
⚪	Generic: Comprehensive Audit Trails Objective: To create a detailed and reliable record of critical system actions for security analysis and compliance. Status: Limited audit logging: The middleware logs rejected unsafe URLs but doesn't log successful redirects with user context (user ID, timestamp), which may be needed for security analysis of redirect patterns. Referred Code console.warn(`[Middleware] Rejected unsafe callbackUrl: ${callbackUrl}`) return NextResponse.redirect(new URL("/dashboard", req.url)) Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Error Handling Objective: To prevent the leakage of sensitive system information through error messages while providing sufficient detail for internal debugging. Status: URL exposure in logs: The warning log exposes the full rejected callbackUrl which could contain sensitive query parameters or tokens that should not be logged. Referred Code console.warn(`[Middleware] Rejected unsafe callbackUrl: ${callbackUrl}`) return NextResponse.redirect(new URL("/dashboard", req.url)) Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Logging Practices Objective: To ensure logs are useful for debugging and auditing without exposing sensitive information like PII, PHI, or cardholder data. Status: Potential sensitive data logging: The callbackUrl logged at line 45 may contain sensitive data in query parameters (tokens, session IDs, user data) that should be sanitized before logging. Referred Code console.warn(`[Middleware] Rejected unsafe callbackUrl: ${callbackUrl}`) return NextResponse.redirect(new URL("/dashboard", req.url)) Learn more about managing compliance generic rules or creating your own custom rules

Compliance status legend

🟢 - Fully Compliant
🟡 - Partial Compliant
🔴 - Not Compliant
⚪ - Requires Further Human Verification
🏷️ - Compliance label

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PR Compliance Guide 🔍

Below is a summary of compliance checks for this PR:

Security Compliance
⚪	Open redirect bypass Description: isSafeRedirectUrl() may be bypassed for open-redirect via backslash/escape normalization (e.g., a callbackUrl like /\evil.com or /%5C%5Cevil.com can be interpreted by URL parsers as a network-path reference //evil.com, causing new URL(callbackUrl, req.url) to redirect off-site despite not matching the simple startsWith("//") / includes("://") checks). url-validation.ts [24-40] Referred Code export function isSafeRedirectUrl(url: string): boolean { // Must start with "/" to be a relative path if (!url.startsWith("/")) { return false } // Must not start with "//" (protocol-relative URL) if (url.startsWith("//")) { return false } // Must not contain "://" which indicates an absolute URL with protocol if (url.includes("://")) { return false } return true
Ticket Compliance
⚪	🎫 No ticket provided Create ticket/issue
Codebase Duplication Compliance
⚪	Codebase context is not defined Follow the guide to enable codebase context checks.
Custom Compliance
🟢	Generic: Meaningful Naming and Self-Documenting Code Objective: Ensure all identifiers clearly express their purpose and intent, making code self-documenting Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Robust Error Handling and Edge Case Management Objective: Ensure comprehensive error handling that provides meaningful context and graceful degradation Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Error Handling Objective: To prevent the leakage of sensitive system information through error messages while providing sufficient detail for internal debugging. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
🔴	Generic: Secure Logging Practices Objective: To ensure logs are useful for debugging and auditing without exposing sensitive information like PII, PHI, or cardholder data. Status: Sensitive data in logs: The new console.warn/console.log statements log the full untrusted callbackUrl, which may contain sensitive data (e.g., tokens or identifiers) and is unstructured. Referred Code console.warn(`[Middleware] Rejected unsafe callbackUrl: ${callbackUrl}`) return NextResponse.redirect(new URL("/dashboard", req.url)) } console.log(`[Middleware] Authenticated user on signin page, redirecting to ${callbackUrl}`) return NextResponse.redirect(new URL(callbackUrl, req.url)) Learn more about managing compliance generic rules or creating your own custom rules
⚪	Generic: Comprehensive Audit Trails Objective: To create a detailed and reliable record of critical system actions for security analysis and compliance. Status: Missing audit context: The new middleware logging records redirect decisions but does not include a user identifier or a structured outcome context needed to reconstruct security-relevant events. Referred Code console.warn(`[Middleware] Rejected unsafe callbackUrl: ${callbackUrl}`) return NextResponse.redirect(new URL("/dashboard", req.url)) } console.log(`[Middleware] Authenticated user on signin page, redirecting to ${callbackUrl}`) return NextResponse.redirect(new URL(callbackUrl, req.url)) Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Security-First Input Validation and Data Handling Objective: Ensure all data inputs are validated, sanitized, and handled securely to prevent vulnerabilities Status: Validation may be bypassable: The new isSafeRedirectUrl uses simple string checks (startsWith("/"), not "//", and not containing "://"), which may not cover URL parser edge-cases (e.g., backslash variants, encoded separators, or other normalization quirks) without additional canonicalization. Referred Code export function isSafeRedirectUrl(url: string): boolean { // Must start with "/" to be a relative path if (!url.startsWith("/")) { return false } // Must not start with "//" (protocol-relative URL) if (url.startsWith("//")) { return false } // Must not contain "://" which indicates an absolute URL with protocol if (url.includes("://")) { return false } return true Learn more about managing compliance generic rules or creating your own custom rules

Compliance status legend

🟢 - Fully Compliant
🟡 - Partial Compliant
🔴 - Not Compliant
⚪ - Requires Further Human Verification
🏷️ - Compliance label

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PR Compliance Guide 🔍

Below is a summary of compliance checks for this PR:

Security Compliance
⚪	Open redirect bypass Description: The new isSafeRedirectUrl() validation is heuristic (string checks for leading /, //, and ://) and may be bypassable via URL parsing/normalization edge-cases (e.g., control characters, backslashes, or percent-encoded sequences that can be interpreted differently across URL resolvers), potentially reintroducing an open-redirect in NextResponse.redirect(new URL(callbackUrl, req.url)). url-validation.ts [24-40] Referred Code export function isSafeRedirectUrl(url: string): boolean { // Must start with "/" to be a relative path if (!url.startsWith("/")) { return false } // Must not start with "//" (protocol-relative URL) if (url.startsWith("//")) { return false } // Must not contain "://" which indicates an absolute URL with protocol if (url.includes("://")) { return false } return true
Ticket Compliance
⚪	🎫 No ticket provided Create ticket/issue
Codebase Duplication Compliance
⚪	Codebase context is not defined Follow the guide to enable codebase context checks.
Custom Compliance
🟢	Generic: Comprehensive Audit Trails Objective: To create a detailed and reliable record of critical system actions for security analysis and compliance. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Meaningful Naming and Self-Documenting Code Objective: Ensure all identifiers clearly express their purpose and intent, making code self-documenting Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Error Handling Objective: To prevent the leakage of sensitive system information through error messages while providing sufficient detail for internal debugging. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
🔴	Generic: Secure Logging Practices Objective: To ensure logs are useful for debugging and auditing without exposing sensitive information like PII, PHI, or cardholder data. Status: Unsafe unstructured logging: The middleware logs the raw user-controlled callbackUrl via console.warn/console.log, which is unstructured and can leak sensitive query parameters or other data into logs. Referred Code console.warn(`[Middleware] Rejected unsafe callbackUrl: ${callbackUrl}`) return NextResponse.redirect(new URL("/dashboard", req.url)) } console.log(`[Middleware] Authenticated user on signin page, redirecting to ${callbackUrl}`) return NextResponse.redirect(new URL(callbackUrl, req.url)) Learn more about managing compliance generic rules or creating your own custom rules
⚪	Generic: Robust Error Handling and Edge Case Management Objective: Ensure comprehensive error handling that provides meaningful context and graceful degradation Status: Incomplete URL validation: The new isSafeRedirectUrl() logic relies on simple string checks and may miss edge-case URL parsing/normalization behaviors (e.g., encoded or unusual separators) that could still lead to unsafe redirects when later passed to new URL(callbackUrl, req.url). Referred Code export function isSafeRedirectUrl(url: string): boolean { // Must start with "/" to be a relative path if (!url.startsWith("/")) { return false } // Must not start with "//" (protocol-relative URL) if (url.startsWith("//")) { return false } // Must not contain "://" which indicates an absolute URL with protocol if (url.includes("://")) { return false } return true Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Security-First Input Validation and Data Handling Objective: Ensure all data inputs are validated, sanitized, and handled securely to prevent vulnerabilities Status: Redirect validation strength: Although callbackUrl is validated with isSafeRedirectUrl(), the validation is based on string patterns only and may not fully cover URL parser normalization edge cases, so the open-redirect fix should be confirmed against framework URL resolution behavior. Referred Code const callbackUrl = req.nextUrl.searchParams.get("callbackUrl") || "/dashboard" // Validate callbackUrl to prevent open redirect vulnerability if (!isSafeRedirectUrl(callbackUrl)) { console.warn(`[Middleware] Rejected unsafe callbackUrl: ${callbackUrl}`) return NextResponse.redirect(new URL("/dashboard", req.url)) } console.log(`[Middleware] Authenticated user on signin page, redirecting to ${callbackUrl}`) return NextResponse.redirect(new URL(callbackUrl, req.url)) Learn more about managing compliance generic rules or creating your own custom rules

Compliance status legend

🟢 - Fully Compliant
🟡 - Partial Compliant
🔴 - Not Compliant
⚪ - Requires Further Human Verification
🏷️ - Compliance label

[qodo-free-for-open-source-projects]

PR Compliance Guide 🔍

Below is a summary of compliance checks for this PR:

Security Compliance
⚪	URL encoding bypass Description: The validation logic checking for :// in the URL can be bypassed using URL-encoded characters (e.g., %3A%2F%2F), allowing attackers to craft malicious redirect URLs that pass validation but decode to absolute URLs when processed by the browser. url-validation.ts [36-38] Referred Code if (url.includes("://")) { return false }
Ticket Compliance
⚪	🎫 No ticket provided Create ticket/issue
Codebase Duplication Compliance
⚪	Codebase context is not defined Follow the guide to enable codebase context checks.
Custom Compliance
🟢	Generic: Meaningful Naming and Self-Documenting Code Objective: Ensure all identifiers clearly express their purpose and intent, making code self-documenting Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Robust Error Handling and Edge Case Management Objective: Ensure comprehensive error handling that provides meaningful context and graceful degradation Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Security-First Input Validation and Data Handling Objective: Ensure all data inputs are validated, sanitized, and handled securely to prevent vulnerabilities Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
⚪	Generic: Comprehensive Audit Trails Objective: To create a detailed and reliable record of critical system actions for security analysis and compliance. Status: Limited audit logging: The middleware logs rejected unsafe URLs with console.warn but does not include user ID, timestamp, or structured logging for security analysis. Referred Code console.warn(`[Middleware] Rejected unsafe callbackUrl: ${callbackUrl}`) return NextResponse.redirect(new URL("/dashboard", req.url)) Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Error Handling Objective: To prevent the leakage of sensitive system information through error messages while providing sufficient detail for internal debugging. Status: URL exposure in logs: The warning log exposes the full callbackUrl value which could potentially contain sensitive query parameters or tokens. Referred Code console.warn(`[Middleware] Rejected unsafe callbackUrl: ${callbackUrl}`) return NextResponse.redirect(new URL("/dashboard", req.url)) Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Logging Practices Objective: To ensure logs are useful for debugging and auditing without exposing sensitive information like PII, PHI, or cardholder data. Status: Unstructured logging format: The middleware uses console.warn with unstructured string interpolation instead of structured JSON logging, and may expose sensitive data in the callbackUrl. Referred Code console.warn(`[Middleware] Rejected unsafe callbackUrl: ${callbackUrl}`) return NextResponse.redirect(new URL("/dashboard", req.url)) Learn more about managing compliance generic rules or creating your own custom rules

Compliance status legend

🟢 - Fully Compliant
🟡 - Partial Compliant
🔴 - Not Compliant
⚪ - Requires Further Human Verification
🏷️ - Compliance label

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PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Security	Use URL constructor for robust validation Refactor isSafeRedirectUrl to use the URL constructor for more robust and secure validation, preventing potential encoding bypasses that simple string checks might miss. frontend/lib/url-validation.ts [24-41] export function isSafeRedirectUrl(url: string): boolean { - // Must start with "/" to be a relative path if (!url.startsWith("/")) { - return false + return false; } - - // Must not start with "//" (protocol-relative URL) - if (url.startsWith("//")) { - return false + + try { + // Use a dummy base URL; it doesn't matter what it is. + const parsedUrl = new URL(url, "http://dummy-base.com"); + + // A safe relative URL will not have its own hostname. + // It will inherit the hostname from the base. + // An absolute or protocol-relative URL (e.g., "//example.com") will have a hostname. + if (parsedUrl.hostname && parsedUrl.hostname !== "dummy-base.com") { + return false; + } + + // Check for dangerous protocols like javascript:, data:, etc. + // Safe relative paths will inherit the base's protocol ('http:'). + if (parsedUrl.protocol !== "http:") { + return false; + } + + return true; + } catch (e) { + // Invalid URL format + return false; } - - // Must not contain "://" which indicates an absolute URL with protocol - if (url.includes("://")) { - return false - } - - return true } Apply / Chat Suggestion importance[1-10]: 9 __ Why: The suggestion correctly identifies that string-based URL validation is fragile and proposes a much more robust and secure implementation using the native URL constructor, which effectively mitigates a class of open redirect bypass vulnerabilities.	High
Possible issue	Update tests for robust URL validation Update the URL validation tests to correctly handle URLs in query parameters as safe relative redirects, and add new tests for actual open redirect vulnerabilities like encoded protocol-relative URLs. frontend/lib/tests/url-validation.test.ts [75-78] -it("rejects URLs trying to bypass with protocols in path", () => { - // These should still be rejected as they contain :// - expect(isSafeRedirectUrl("/redirect?url=https://evil.com")).toBe(false) -}) +it("rejects protocol-relative URLs that could be used for open redirects", () => { + expect(isSafeRedirectUrl("//evil.com")).toBe(false); + // Encoded slashes + expect(isSafeRedirectUrl("/%2fevil.com")).toBe(false); + expect(isSafeRedirectUrl("%2f%2fevil.com")).toBe(false); +}); +it("allows query parameters containing URLs", () => { + // This is a safe relative redirect. The `url` param is just data. + expect(isSafeRedirectUrl("/redirect?url=https://evil.com")).toBe(true); +}); + Apply / Chat Suggestion importance[1-10]: 7 __ Why: The suggestion correctly points out a conceptual error in the original test case, clarifying that a URL within a query parameter of a relative path is not an open redirect. It proposes updating the test to reflect correct behavior and adds more relevant test cases.	Medium
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Category	Suggestion	Impact
Security	Fix open redirect vulnerability from encoding Fix an open redirect vulnerability by repeatedly decoding the URL before checking for protocol markers like ://. This handles multiple layers of encoding to reveal and reject hidden absolute URLs. frontend/lib/url-validation.ts [24-41] export function isSafeRedirectUrl(url: string): boolean { - // Must start with "/" to be a relative path if (!url.startsWith("/")) { return false } - - // Must not start with "//" (protocol-relative URL) + if (url.startsWith("//")) { return false } - - // Must not contain "://" which indicates an absolute URL with protocol - if (url.includes("://")) { + + // To prevent open redirect vulnerabilities with encoded characters, + // we need to check the decoded version of the URL. + // We decode repeatedly to handle multiple layers of encoding. + let decodedUrl = url + try { + while (decodedUrl !== decodeURIComponent(decodedUrl)) { + decodedUrl = decodeURIComponent(decodedUrl) + } + } catch (e) { + // A malformed URI is suspicious and should be rejected. return false } - + + if (decodedUrl.includes("://")) { + return false + } + return true } Apply / Chat Suggestion importance[1-10]: 10 __ Why: This suggestion correctly identifies and fixes a critical open redirect vulnerability by implementing robust, repeated URL decoding, which the original code completely lacks.	High
Possible issue	Correct test case for encoded URLs Update the test case for encoded characters to assert that URLs containing encoded absolute URLs are correctly identified as unsafe. This change ensures the test validates against open redirect attacks. frontend/lib/tests/url-validation.test.ts [70-73] -it("handles URLs with encoded characters", () => { - expect(isSafeRedirectUrl("/path?url=http%3A%2F%2Fevil.com")).toBe(true) // encoded as query param is OK - expect(isSafeRedirectUrl("/path%2F..%2F..%2Fetc")).toBe(true) // path traversal encoded is still a relative path +it("rejects URLs with encoded protocol markers", () => { + // Single encoding + expect(isSafeRedirectUrl("/path?url=http%3A%2F%2Fevil.com")).toBe(false) + // Double encoding + expect(isSafeRedirectUrl("/path?url=http%253A%252F%252Fevil.com")).toBe(false) + // Path traversal is a relative path, but should be handled by the framework/server. + // The validation function's job is to prevent redirects to other domains. + expect(isSafeRedirectUrl("/path%2F..%2F..%2Fetc")).toBe(true) }) Apply / Chat Suggestion importance[1-10]: 9 __ Why: This suggestion correctly identifies a flawed test case that validates a security vulnerability as acceptable behavior. Correcting this test is crucial for ensuring the security fix is effective and regression-proof.	High
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Category	Suggestion	Impact
Security	Prevent potential path traversal vulnerabilities Update the test for encoded URLs to assert that encoded path traversal attempts are unsafe, preventing potential security vulnerabilities. frontend/lib/tests/url-validation.test.ts [70-73] it("handles URLs with encoded characters", () => { expect(isSafeRedirectUrl("/path?url=http%3A%2F%2Fevil.com")).toBe(true) // encoded as query param is OK - expect(isSafeRedirectUrl("/path%2F..%2F..%2Fetc")).toBe(true) // path traversal encoded is still a relative path }) +it("rejects encoded path traversal attempts", () => { + // Decoded: /path/../../etc + expect(isSafeRedirectUrl("/path%2F..%2F..%2Fetc")).toBe(false) + // Decoded: /../ + expect(isSafeRedirectUrl("/%2E%2E/")).toBe(false) +}) + Apply / Chat Suggestion importance[1-10]: 9 __ Why: This suggestion correctly identifies a significant security flaw (path traversal) in the new validation logic and proposes updating the tests to catch it, which is critical for ensuring the feature is secure.	High
	Add check for encoded path traversal Add a check to isSafeRedirectUrl to detect and reject encoded path traversal sequences like %2F.. to mitigate a security vulnerability. frontend/lib/url-validation.ts [24-41] export function isSafeRedirectUrl(url: string): boolean { // Must start with "/" to be a relative path if (!url.startsWith("/")) { return false } // Must not start with "//" (protocol-relative URL) if (url.startsWith("//")) { return false } // Must not contain "://" which indicates an absolute URL with protocol if (url.includes("://")) { return false } + + // Prevent path traversal attacks with encoded slashes + if (url.includes("%2F..") || url.includes("..%2F")) { + return false + } return true } Apply / Chat Suggestion importance[1-10]: 9 __ Why: This suggestion provides a direct and effective fix for a significant path traversal security vulnerability in the isSafeRedirectUrl function, making the application more secure.	High
General	Remove redundant code for simplicity Remove the redundant url.startsWith("//") check from isSafeRedirectUrl as it is already covered by the !url.startsWith("/") condition. frontend/lib/url-validation.ts [24-41] export function isSafeRedirectUrl(url: string): boolean { - // Must start with "/" to be a relative path + // Must start with "/" to be a relative path and not be a protocol-relative URL if (!url.startsWith("/")) { return false } - // Must not start with "//" (protocol-relative URL) - if (url.startsWith("//")) { - return false - } - - // Must not contain "://" which indicates an absolute URL with protocol + // Must not contain "://" which indicates an absolute URL with a protocol if (url.includes("://")) { return false } return true } Apply / Chat Suggestion importance[1-10]: 3 __ Why: The suggestion correctly identifies a redundant check, and removing it simplifies the code without altering its logic, which is a good practice for maintainability.	Low
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PR Code Suggestions ✨

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Category	Suggestion	Impact
Security	Prevent open redirect vulnerability Fix an open redirect vulnerability in isSafeRedirectUrl by decoding the URL with decodeURIComponent before checking for protocol markers like ://. This prevents attackers from bypassing the check using URL-encoded characters. frontend/lib/url-validation.ts [24-41] -export function isSafeRedirectUrl(url: string): boolean { +export function isSafeRedirectUrl(url:string): boolean { // Must start with "/" to be a relative path if (!url.startsWith("/")) { return false } - + // Must not start with "//" (protocol-relative URL) if (url.startsWith("//")) { return false } - - // Must not contain "://" which indicates an absolute URL with protocol - if (url.includes("://")) { - return false + + try { + // Decode the URL to prevent bypasses with encoded characters (e.g., %3A%2F%2F) + const decodedUrl = decodeURIComponent(url); + + // Must not contain "://" which indicates an absolute URL with a protocol + if (decodedUrl.includes("://")) { + return false + } + } catch (e) { + // A malformed URI is not a safe redirect URL. + return false; } - + return true } Apply / Chat Suggestion importance[1-10]: 10 __ Why: This suggestion addresses a critical open redirect vulnerability by correctly identifying that the current implementation can be bypassed with URL-encoded payloads. The proposed fix using decodeURIComponent is the correct approach to make the validation robust.	High
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[Copilot]

Pull request overview

This PR addresses an open redirect vulnerability in the authentication middleware by implementing URL validation for the callbackUrl parameter. However, the implementation has critical flaws that need to be addressed before merging.

Changes:

• Created isSafeRedirectUrl() utility function to validate redirect URLs
• Updated middleware to validate callbackUrl before redirecting authenticated users
• Added 14 test cases covering various URL patterns and edge cases
• Added jsdom dependency for testing and updated .gitignore

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
frontend/lib/url-validation.ts	New utility function to validate safe redirect URLs - has critical logic flaw
frontend/middleware.ts	Applies URL validation to callbackUrl parameter before redirecting
frontend/lib/tests/url-validation.test.ts	Comprehensive test suite with 14 test cases - contains incorrect test expectation
frontend/package.json	Adds jsdom dependency for DOM testing
frontend/.gitignore	Adds package-lock.json to ignore list

---

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[Copilot]

The validation logic incorrectly rejects legitimate relative URLs that contain "://" in their query parameters. For example, /redirect?url=https://evil.com is a safe relative path - the user would be redirected to /redirect with a query parameter, not to https://evil.com. This creates a false positive that would break legitimate use cases where URLs are passed as query parameters.

The validation should only reject the URL if the protocol appears in the path component itself before any query parameters, not in query string values. Consider parsing the URL to check only the pathname, or at minimum, check if "://" appears before the first "?" character.

Suggested change

	// Must not contain "://" which indicates an absolute URL with protocol
	if (url.includes("://")) {
	// Must not contain "://" in the path portion (before any "?"), which indicates an absolute URL with protocol
	const queryIndex = url.indexOf("?")
	const pathPart = queryIndex === -1 ? url : url.slice(0, queryIndex)
	if (pathPart.includes("://")) {

[Copilot]

This test has an incorrect expectation. The URL /redirect?url=https://evil.com is actually a safe relative path - it redirects to the /redirect page with https://evil.com as a query parameter value. The current validation function correctly identifies this as unsafe due to the includes("://") check, but this is a false positive that would break legitimate use cases.

The test comment states "These should still be rejected as they contain ://", but this reasoning is flawed - the presence of "://" in query parameter values does not make a relative URL unsafe. Update this test to expect true instead of false, or remove it if the validation logic is fixed to properly handle query parameters.

Suggested change

	// These should still be rejected as they contain ://
	expect(isSafeRedirectUrl("/redirect?url=https://evil.com")).toBe(false)
	// A relative URL is safe even if a query parameter contains ://
	expect(isSafeRedirectUrl("/redirect?url=https://evil.com")).toBe(true)

[Copilot]

The validation does not check for backslash-based bypass attempts. In some browsers and URL parsing contexts, backslashes can be normalized to forward slashes. For example, URLs like /\example.com or /\\example.com might be interpreted as //example.com in certain contexts, creating a protocol-relative URL bypass.

Consider adding validation to reject URLs containing backslashes, or at minimum, add test coverage for these edge cases to verify the behavior of the new URL() constructor in Next.js middleware with backslash-containing URLs.

Suggested change

	}
	}
	// Must not contain backslashes, which some parsers normalize to "/"
	if (url.includes("\\")) {
	return false
	}

[Copilot]

The validation does not handle URLs with leading or trailing whitespace, or URLs containing tab/newline characters. While the middleware extracts the callbackUrl from URL search parameters (which typically handles URL encoding), it's a security best practice to explicitly trim and sanitize the input.

Consider adding url.trim() at the beginning of the validation function, and potentially checking for or stripping control characters (tabs, newlines, etc.) that could be used in bypass attempts.

[Copilot]

Test coverage is missing for several important edge cases that could be security vulnerabilities:

1. Backslash-based bypasses: /\example.com or /\\example.com
2. Whitespace handling: URLs with leading/trailing whitespace like " /dashboard" or "/dashboard "
3. URLs with control characters (tabs, newlines): /dashboard\t, /dashboard\n
4. Mixed case protocol attempts: /HtTpS://evil.com (though this would likely be caught by the current logic)

Add test cases for these scenarios to ensure the validation handles them correctly and doesn't have bypass vulnerabilities.