[CLSA-2026:1790182556] Fix CVE(s): CVE-2026-82049
Type:
security
Severity:
Important
Release date:
2026-09-23 16:56:08 UTC
Description:
* SECURITY UPDATE: tarfile PEP 706 "data"/"tar" extraction filter bypass via a hard link to a symlink. A crafted archive whose hard link names a symlink stored deeper in the archive made makelink_with_filter() call os.link() on the unresolved source; link(2) does not follow symlinks, so the extracted member became the same symlink inode under the hard link's own, shallower name, where its relative payload re-bases outside the destination. The chmod()/utime() that tarfile applies next then hit the outside file, changing its mode and mtime, and its contents became readable from inside the extracted tree (CWE-59). - debian/patches/CVE-2026-82049.patch: backport of cpython b8f23e307097552eaea2604383a12ab280520d0d (gh-157190, GH-157191, GH-157192), the 3.13-branch form of the fix; the changed line and its comment are upstream's verbatim, only re-anchored because this tree has no "unlink an existing targetpath" step before os.link(). The upstream regression test test_sneaky_hardlink_relocation is carried too, minus the @symlink_test / @os_helper.skip_unless_hardlink decorators and with os_helper.can_symlink() spelled support.can_symlink(), neither of which exists in 3.6. - The one-line fix closes only the variant where the archive carries a decoy file at the outer name, so os.path.exists(tarinfo._link_target) is true and extraction goes through os.link(). The decoy-less variant never reaches os.link() at all; under the "data" filter it is rejected by CVE-2026-11940.patch, already in this package, so the two must not be separated. - CVE-2026-82049 * The Misc/NEWS.d fragment of the upstream commit is omitted; this version ships a single Misc/NEWS file.
CVEs fixed:
Updated packages:
  • alt-python36_3.6.15-47_amd64.deb
    sha:a8b673326ff7b6168a32276d4aea396fd2bddebf
  • alt-python36-debug_3.6.15-47_amd64.deb
    sha:cf2587af882547e208034a8fe13e2eb927391552
  • alt-python36-devel_3.6.15-47_amd64.deb
    sha:04653d071b4269313030f9e200981ec598102d6f
  • alt-python36-libs_3.6.15-47_amd64.deb
    sha:2f35d8e1679ff09e7cf80e173a30187f61c4429e
  • alt-python36-test_3.6.15-47_amd64.deb
    sha:51edaf2197a03883e459c3910ce033ecfbff1e5e
  • alt-python36-tkinter_3.6.15-47_amd64.deb
    sha:f6a53492a284157c2cef6af1aa4233f8ad9eef53
  • alt-python36-tools_3.6.15-47_amd64.deb
    sha:d2047b8a7b641474106fd60958b15b6b9a7c4005
Notes:
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