[oss-security][CVE-2026-7774] Cpython: tarfile.data_filter path traversal bypass allows writing outside the extraction directory

[Alan Coopersmith <alan.coopersmith () oracle com>]

https://www.cve.org/CVERecord?id=CVE-2026-7774 currently lists affected
versions as "from 0 before 3.15.0".


-------- Forwarded Message --------
Subject: 	[Security-announce][CVE-2026-7774] tarfile.data_filter path traversal 
bypass allows writing outside the extraction directory
Date:   Thu, 4 Jun 2026 15:12:43 +0100
From:   Stan Ulbrych via Security-announce <security-announce () python org>
Reply-To:       security-sig () python org
To:     security-announce () python org
CC:     Stan Ulbrych <stanulbrych () gmail com>



There is a MEDIUM severity vulnerability affecting CPython.

tarfile.data_filter could be bypassed using crafted link entries, including
symlinks with empty or directory-like names, to redirect later archive members
outside the intended extraction directory. This allowed a malicious tar archive
to cause tarfile.extractall() to write files outside the destination directory,
subject to the permissions of the extracting process.

Please see the linked CVE ID for the latest information on affected versions:

* https://www.cve.org/CVERecord?id=CVE-2026-7774
* https://github.com/python/cpython/pull/149487

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