CVE-2026-55206
py7zr: O(n^2) algorithmic complexity DoS in PackInfo._read()
CVSS Score
0.0
EPSS Score
0.3%
EPSS Percentile
24th
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.
| CWE | CWE-407 |
| Vendor | miurahr |
| Product | py7zr |
| Published | Jul 8, 2026 |
| Last Updated | Jul 9, 2026 |
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Affected Versions
miurahr / py7zr
< 1.1.3