[oss-security][CVE-2026-3087] shutil.unpack_archive() doesn't check for Windows absolute paths in ZIPs

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

-------- Forwarded Message --------
Subject: 	[Security-announce][CVE-2026-3087] shutil.unpack_archive() doesn't 
check for Windows absolute paths in ZIPs
Date:   Mon, 27 Apr 2026 20:48:33 +0000
From:   Seth Larson <seth () python org>
Reply-To:       security-sig () python org
To:     security-announce () python org



There is a MEDIUM severity vulnerability affecting CPython.

If `shutil.unpack_archive()` is given a ZIP archive with an absolute Windows 
path containing a drive (`C:\\...`) then the archive will be extracted outside 
the target directory which is different than other operating systems. Only 
Windows is affected by this vulnerability.

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

* https://www.cve.org/CVERecord?id=CVE-2026-3087
* https://github.com/python/cpython/pull/146591

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