Python CPython tarfile link extraction double-filter flaw (3.15)
CVE-2026-87910 Published on September 11, 2026
tarfile hardlink fallback ignores custom extraction filter rejection via None
When tarfile extracts a link on a system that doesn't support links, it falls back to extracting a member from the archive. In this case, the filter function is run twice: once for the extracted member, and once with name set to the location of the link. For one of the calls, the return value was ignored. Instead, the member should be skipped if either call returns None.
Vulnerability Analysis
CVE-2026-87910 is exploitable with network access. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Types
What is a Directory traversal Vulnerability?
The software uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the software does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
CVE-2026-87910 has been classified to as a Directory traversal vulnerability or weakness.
What is an insecure temporary file Vulnerability?
The software attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
CVE-2026-87910 has been classified to as an insecure temporary file vulnerability or weakness.
Products Associated with CVE-2026-87910
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Affected Versions
Python Software Foundation CPython:- Before 3.15.0 is affected.