tarfile hardlink fallback ignores custom extraction filter rejection via None (CVE-2026-87910) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-87910

tarfile hardlink fallback ignores custom extraction filter rejection via None

Answer in brief

CVE-2026-87910 records a Unknown severity vulnerability in tarfile hardlink fallback ignores custom extraction filter rejection via None. The current sources do not mark it as known exploited. The current feed maps Python Software Foundation/CPython (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 11, 2026Updated Sep 11, 2026Source checked Sep 11, 2026First seen by HOL Sep 11, 2026Material review Sep 11, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Python Software Foundation/CPython (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Python Software Foundation/CPythongeneric	>=0 <3.16.0	3.16.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for Python Software Foundation/CPython.
Review the reported fix. Update Python Software Foundation/CPython to 3.16.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 11, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.