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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-6100 Detail

Description

Use-after-free (UAF) was possible in the `lzma.LZMADecompressor`, `bz2.BZ2Decompressor`, and `gzip.GzipFile` when a memory allocation fails with a `MemoryError` and the decompression instance is re-used. This scenario can be triggered if the process is under memory pressure. The fix cleans up the dangling pointer in this specific error condition. The vulnerability is only present if the program re-uses decompressor instances across multiple decompression calls even after a `MemoryError` is raised during decompression. Using the helper functions to one-shot decompress data such as `lzma.decompress()`, `bz2.decompress()`, `gzip.decompress()`, and `zlib.decompress()` are not affected as a new decompressor instance is used per call. If the decompressor instance is not re-used after an error condition, this usage is similarly not vulnerable.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

Nist CVSS score does not match with CNA score
CNA:  Python Software Foundation
CVSS-B 9.1 CRITICAL
Vector:  CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
http://www.openwall.com/lists/oss-security/2026/04/13/10 CVE
https://github.com/python/cpython/commit/47128e64f98c3a20271138a98c2922bea2a3ee0e Python Software Foundation
https://github.com/python/cpython/commit/6a5f79c8d7bbf22b083b240910c7a8781a59437d Python Software Foundation
https://github.com/python/cpython/commit/8fc66aef6d7b3ae58f43f5c66f9366cc8cbbfcd2 Python Software Foundation
https://github.com/python/cpython/commit/c3cf71c3366fe49acb776a639405c0eea6169c20 Python Software Foundation
https://github.com/python/cpython/commit/e20c6c9667c99ecaab96e1a2b3767082841ffc8b Python Software Foundation
https://github.com/python/cpython/issues/148395 Python Software Foundation
https://github.com/python/cpython/pull/148396 Python Software Foundation
https://mail.python.org/archives/list/[email protected]/thread/HTWB2Z6KT5QQX4RYEZAFININDHNOSIF3/ Python Software Foundation

Weakness Enumeration

CWE-ID CWE Name Source
CWE-416 Use After Free Python Software Foundation  
CWE-787 Out-of-bounds Write Python Software Foundation  

Change History

3 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-6100
NVD Published Date:
04/13/2026
NVD Last Modified:
04/17/2026
Source:
Python Software Foundation