Bug 2498255 (CVE-2026-55195)

Summary: CVE-2026-55195 py7zr: py7zr: Denial of Service via decompression bomb in 7zip archive extraction
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: jmitchel, kshier, pbohmill, teagle
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in py7zr, a Python library for 7zip archive handling. This vulnerability allows a remote attacker to cause a Denial of Service (DoS) by providing a specially crafted .7z file. The `Worker.decompress()` function fails to track the total decompressed size, enabling a small archive to expand significantly and exhaust system resources such as disk space or memory during extraction. This issue is also known as a decompression bomb (CWE-409).
Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-07-08 21:02:16 UTC
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.