Properly sanitize attachment filenames#118
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The-Compiler wants to merge 1 commit intoakissinger:masterfrom
Open
Properly sanitize attachment filenames#118The-Compiler wants to merge 1 commit intoakissinger:masterfrom
The-Compiler wants to merge 1 commit intoakissinger:masterfrom
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The "filename" field from notmuch seems to originate directly from the email's Content-Disposition header. It's not guaranteed that the suggested filename is supported on the current filesystem, or that it is safe. For example, filenames may contain path separators, which could lead to files being written outside of the intended directory. This can be a security risk, as e.g. an attacker could craft an email that uses "../../home/user/.bashrc" as attachment filename, causing that file to be overwritten when attachments are viewed. A minimal mitigation is to strip path separators from attachment filenames before using them, but this commit properly sanitizes more aspects of the filename (invalid characters on different OS and path length limits), using code from qutebrowser which has been used in production for multiple years (originally written by me, slightly simplified and adapted): https://github.com/qutebrowser/qutebrowser/blob/5d14f90ded9377b857dbe1147297d5e33535494a/qutebrowser/utils/utils.py#L441-L508
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The "filename" field from notmuch seems to originate directly from the email's Content-Disposition header. It's not guaranteed that the suggested filename is supported on the current filesystem, or that it is safe.
For example, filenames may contain path separators, which could lead to files being written outside of the intended directory. This can be a security risk, as e.g. an attacker could craft an email that uses "../../home/user/.bashrc" as attachment filename, causing that file to be overwritten when attachments are viewed.
A minimal mitigation is to strip path separators from attachment filenames before using them, but this commit properly sanitizes more aspects of the filename (invalid characters on different OS and path length limits), using code from qutebrowser which has been used in production for multiple years (originally written by me, slightly simplified and adapted): https://github.com/qutebrowser/qutebrowser/blob/5d14f90ded9377b857dbe1147297d5e33535494a/qutebrowser/utils/utils.py#L441-L508