CVE-2026-55206

unknowncovered by 1 sourcefirst seen 2026-07-08

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.

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Exploitation outlook

Low exploitation risk0.32% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 24% of all EPSS-scored CVEs.

Advisory coverage (1)

unknownCVE-2026-55206: py7zr is a Python-based library and utility to support 7zip archive compression, decompression…nvd · 2026-07-08

External references

NVD record for CVE-2026-55206

CVE.org record

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