GeezerVison is showing github.com — [3.13] gh-149486: tarfile.data_filter: validate written link target (GH-149487) by miss-islington · Pull Request #149555 · python/cpython
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miss-islington
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May 8, 2026
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edited by bedevere-app
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The data filter rewrote linknames with normpath() but ran the
containment check against the un-normalised value, and computed a
symlink's directory before stripping trailing slashes. Both let a
crafted archive create links pointing outside the destination. Also
reject link members that resolve to the destination directory itself,
which could otherwise replace it with a symlink and redirect all
subsequent members.
(Patch by Greg; Petr's just reviewing & merging.)
(cherry picked from commit 5784119)
Co-authored-by: Petr Viktorin [email protected]
Co-authored-by: Gregory P. Smith [email protected]
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…ythonGH-149487)
The data filter rewrote linknames with normpath() but ran the
containment check against the un-normalised value, and computed a
symlink's directory before stripping trailing slashes. Both let a
crafted archive create links pointing outside the destination. Also
reject link members that resolve to the destination directory itself,
which could otherwise replace it with a symlink and redirect all
subsequent members.
(Patch by Greg; Petr's just reviewing & merging.)
(cherry picked from commit 5784119)
Co-authored-by: Petr Viktorin <[email protected]>
Co-authored-by: Gregory P. Smith <[email protected]>
This was referenced May 8, 2026
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ethanfurman
Awaiting requested review from ethanfurman
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