CVE-2026-55206 — py7zr: O(n^2) algorithmic complexity DoS in PackInfo._read()
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 use…
Published: 2026-07-08 · CVSS: 8.7 · CVSS 4.0
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7