Runbook: Incident Q27IUX3O3X3EKP – orchardcorecmsweb2 Admin Page IndexOutOfRangeException

[mrsharm]

This issue tracks the runbook generated from PagerDuty incident Q27IUX3O3X3EKP and follow-ups for hardening and verification.

Links

• PagerDuty Incident: https://microsoft-sre-agent-test.pagerduty.com/incidents/Q27IUX3O3X3EKP

Incident Summary

• Priority: P1
• Urgency: high
• Title: orchardcorecmsweb2 - IndexOutOfRangeException resulting in Admin Page Breaking
• Created: 2026-01-17T23:05:23Z
• Updated: 2026-02-04T11:07:47Z
• Service: Test Service (PW921HP)
• Status (at time of runbook generation): triggered

Impact

• Admin dashboard became inaccessible for orchardcorecmsweb2 due to an unhandled IndexOutOfRangeException triggered by User-Agent parsing in DashboardController.ExtractCriticalSegment().

Detection / Trigger

• Alert from Security audit system / application errors raised an incident. The exception type and message recorded:
  • Exception Type: IndexOutOfRangeException
  • Message: Index was outside the bounds of the array
  • Source: Security audit system - User-Agent parsing failure
  • Component: DashboardController.ExtractCriticalSegment()
  • Timestamp: 2026-01-17 22:14:56.978

Timeline (key points)

• 2026-01-17 22:14:56.978: Exception thrown during request processing; admin page breaks.
• 2026-01-17 23:05:23Z: Incident created in PagerDuty (P1, high urgency).
• Subsequent: Temporary bypass of User-Agent parsing applied to restore access.
• Subsequent: Bounds checks and robust parsing added; fix deployed.

Root Cause Analysis

• AI-identified root cause: Unvalidated input parsing.
• Parsing logic assumes fixed structure and indexes into arrays/lists without bounds checks. Malformed/unexpected User-Agent strings cause out-of-range access and unhandled exceptions.

Diagnostics Performed

• Reviewed exception logs and component (DashboardController.ExtractCriticalSegment).
• Correlated failures with specific malformed User-Agent strings from the Security audit system context.
• Verified that bypassing the parsing removed the immediate failure.

Mitigation / Remediation Steps

1. Immediate mitigation: Temporarily bypass User-Agent parsing for affected requests to restore admin access.
2. Remediation: Add bounds checks and defensive parsing around array/list access in ExtractCriticalSegment(). Handle malformed or unexpected User-Agent formats gracefully.
3. Deployment: Redeploy the application with the parsing fix.

Verification / Validation

• After fix deployment, verify:
  • No IndexOutOfRangeException occurrences in logs for the component.
  • Admin dashboard loads successfully under various User-Agent inputs, including deliberately malformed cases.
  • Synthetic checks for admin routes succeed.

Current Status

• Incident currently reported as triggered in metadata but notes include a resolution entry; ensure production currently has the robust parsing deployed and monitored.

Follow-ups / Action Items

• Add unit tests covering boundary conditions for User-Agent parsing, including empty, extremely short, and corrupted values. Owner: Backend maintainers. Due: ASAP.
• Add structured validation utilities for request header parsing with length and null checks. Owner: Platform team. Due: ASAP.
• Create synthetic tests for admin endpoints with diverse User-Agent headers. Owner: QA/Testing. Due: ASAP.
• Add dashboards/alerts for exception rates on DashboardController.ExtractCriticalSegment. Owner: SRE/Observability. Due: ASAP.
• Post-incident review to confirm no similar unchecked indexing patterns exist in adjacent parsing code. Owner: Backend maintainers. Due: 1 week.

Notes

• PD note recorded: "Resolution Note: DONE" by Dheeraj Bandaru; reconcile with current deployment status.

Requested Labels

• incident, runbook, pagerduty, P1, cpu-app

Please use this issue to track completion of the follow-ups and link any PRs implementing the parsing fix and tests.

This issue was created by mrsharm-sri1111--3f136ed8
Tracked by the SRE agent here