Update TAR guidance for untrusted archives - #54670
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…ributes Adds security guidance to the ZIP/TAR best-practices article for handling untrusted TAR archives: - A note that destination boundary validation assumes the destination is a real directory the app controls; a junction/symlink destination (or parent) causes extraction to follow the link, even with TarFile.ExtractToDirectory. - A new section on PAX extended attributes and link names as untrusted, archive-supplied input that can override header fields. - Updated the untrusted-metadata checklist item to include link names and PAX extended attributes. Co-authored-by: Copilot <[email protected]>
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Pull request overview
Updates the archive security best-practices guidance to cover TAR-specific risks when extracting untrusted archives, complementing the existing ZIP guidance.
Changes:
- Adds a note clarifying the limits of destination boundary validation when the destination path contains junctions or symlinks.
- Documents TAR PAX extended attributes and TAR link names as untrusted metadata that requires validation and limits.
- Updates the best-practices checklist to explicitly include TAR link names and PAX extended attributes.
gewarren
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Jul 8, 2026
Co-authored-by: Genevieve Warren <[email protected]>
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@copilot can you please apply the review suggested text changes? |
Co-authored-by: Copilot <[email protected]>
GrabYourPitchforks
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Jul 8, 2026
…chive note The note lives in the streaming/untrusted-input section, but referenced TarFile.ExtractToDirectory, which the article frames as a trusted-input convenience API. Reword to keep the note focused on manual boundary validation and avoid the inconsistency. Co-authored-by: Copilot <[email protected]>
gewarren
enabled auto-merge (squash)
July 29, 2026 17:13
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Updating the ZIP/TAR best-practices docs with security guidance for TAR API use: destination boundary validation, PAX extended attributes, and link names.
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