What’s Vulnerable › Vulnerabilities

CVE-2026-55195: py7zr: Decompression bomb (zip bomb) denial of service via unchecked extraction size

• Severity: high (CVSS 8.7 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-08 · updated 2026-10-25
• Weakness: CWE-409

Description

py7zr is a Python-based library and utility to support 7zip archive compression, decompression, encryption and decryption. Prior to 1.1.3, py7zr's Worker.decompress() extracted archive entries without tracking total decompressed size, allowing a crafted .7z file such as a 15.6 KB archive that expands to 100 MB to exhaust disk or memory before extraction completes. This issue is fixed in version 1.1.3.

Affected products

• miurahr py7zr: before 1.1.3

References

• https://github.com/miurahr/py7zr/commit/28faf107b64374fa5a02bfb93aa2024e281ca97b
• https://github.com/miurahr/py7zr/releases/tag/v1.1.3
• https://github.com/miurahr/py7zr/security/advisories/GHSA-gjrg-mpp7-g774
• https://github.com/miurahr/py7zr/security/advisories/GHSA-gjrg-mpp7-g774

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