zipfile: bzip2/LZMA/Zstandard members decompress without a max_length bound, defeating chunked-read memory limits (CVE-2026-15310) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-15310

zipfile: bzip2/LZMA/Zstandard members decompress without a max_length bound, defeating chunked-read memory limits

Answer in brief

CVE-2026-15310 records a Unknown severity vulnerability in zipfile: bzip2/LZMA/Zstandard members decompress without a max_length bound, defeating chunked-read memory limits. 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 Aug 25, 2026Updated Aug 25, 2026Source checked Aug 25, 2026First seen by HOL Aug 25, 2026Material review Aug 25, 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
Aug 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 25, 2026

Sources and claim methodology

Upstream source description

When decompressing crafted zip files using the bzip/LZMA/Zstandard compressions, Python could use an attacker-controlled size to pre-allocate memory, possibly resulting in memory exhaustion.

Quoted source text, attributed separately from HOL analysis.