-------- Forwarded Message --------
Subject: [Security-announce][CVE-2026-12345] Race condition in
tempfile.TemporaryDirectory cleanup allows deleting files outside the temporary
directory
Date: Tue, 29 Sep 2026 18:28:51 +0100
From: Stan Ulbrych via Security-announce <[email protected]>
Reply-To: [email protected]
To: [email protected]
CC: Stan Ulbrych <[email protected]>
There is a MEDIUM severity vulnerability affecting CPython.
The cleanup of tempfile.TemporaryDirectory is vulnerable to a race condition. An
attacker who can modify the tree during cleanup can replace a directory with a
symbolic link, causing files outside of the temporary directory to be deleted or
have their permissions and file flags reset, with the privileges of the process
performing the cleanup.
Note that platforms where shutil.rmtree.avoids_symlink_attacks is false, remain
affected, and file flags may still be reset outside of the tree on all platforms.
Please see the linked CVE ID for the latest information on affected versions:
* https://www.cve.org/CVERecord?id=CVE-2026-12345
* https://github.com/python/cpython/pull/157580
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