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CVE-2026-15310

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

LOW
2.1
CVSS Score
Published: August 25, 2026 at 03:07 PM UTC
Updated: October 2, 2026 at 01:16 AM UTC
1 product affected across 1 vendorPython

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Severity
LOW2.1
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Python· Python
60%
v < 3.10.223.11.0 ≤ v < 3.11.173.12.0 ≤ v < 3.12.153.13.0 ≤ v < 3.13.163.14.0 ≤ v < 3.14.83.15.0a1 ≤ v < 3.15.0rc23.11.03.12.03.13.03.14.03.15.0a1
Affected range stops below 3.10.22, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.11.17, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.12.15, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.13.16, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.14.8, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.15.0rc2, so it looks safe — our inference, not a vendor statement

References (13)

Issue Tracking
Source: [email protected]
https://github.com/python/cpython/issues/156002
Patch
Source: [email protected]
https://github.com/python/cpython/pull/156003
Vendor Advisory
Source: [email protected]
https://mail.python.org/archives/list/[email protected]/thread/YUHXURX2WZGKGNA4ANYBQS2VZRYQ5JNK/
Patch
Source: cverecord
https://github.com/python/cpython/commit/f897dbf2f36a5935700b7c2d94d4681d2136b7d4
Patch
Source: cverecord
https://github.com/python/cpython/commit/1b424c0178a01e155fd0267dc28a8fc1159b33a8
Patch
Source: cverecord
https://github.com/python/cpython/commit/31980e84b9a708424a0a1dfecde3fc991e313f89
Patch
Source: cverecord
https://github.com/python/cpython/commit/e2311cfb3dd518f008f312fe0631f4f7490d237a
Patch
Source: cverecord
https://github.com/python/cpython/commit/f507e6946a3194e83e1d7b8ee6e14567175e46de

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

2.1LOWPSF
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-400

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