CVE-2026-55206 | THREATINT

Description

py7zr is a Python-based library and utility to support 7zip archive compression, decompression, encryption and decryption. Prior to 1.1.3, PackInfo._read() in archiveinfo.py used an O(n^2) cumulative sum pattern for attacker-controlled numstreams values parsed from archive headers, allowing a crafted .7z archive to cause excessive CPU consumption during SevenZipFile.init() before extraction. This issue is fixed in version 1.1.3.

PUBLISHED Reserved 2026-06-16 | Published 2026-07-08 | Updated 2026-07-08 | Assigner GitHub_M

HIGH: 8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Problem types

CWE-407: Inefficient Algorithmic Complexity

Product status

< 1.1.3

affected

References

github.com/.../py7zr/security/advisories/GHSA-h4gh-22qq-72r7

github.com/...ommit/d7aa3a197d15c75a65b24f796d3a69f83806d3f8

github.com/miurahr/py7zr/releases/tag/v1.1.3

cve.org (CVE-2026-55206)

nvd.nist.gov (CVE-2026-55206)

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