CVE-2026-55206
Published:July 08, 2026
Updated:July 20, 2026
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.
Affected Packages
py7zr (CONDA):
Affected version(s) >=0.16.1 <1.1.3Fix Suggestion:
Update to version 1.1.3https://github.com/miurahr/py7zr.git (GITHUB):
Affected version(s) >=v0.0.3 <v1.1.3Fix Suggestion:
Update to version v1.1.3py7zr (PYTHON):
Affected version(s) >=0.0.3 <1.1.3Fix Suggestion:
Update to version 1.1.3Related Resources (7)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Inefficient Algorithmic Complexity
EPSS
Base Score:
0.32