Bug 2492507 (CVE-2026-23879)

Summary: CVE-2026-23879 py7zr: py7zr: Arbitrary file write via crafted symbolic links during archive extraction
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: jmitchel, kshier, pbohmill, teagle
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in py7zr. An attacker can craft a malicious archive containing symbolic links that, when extracted, can lead to arbitrary file writes outside the intended directory. This vulnerability may allow for remote code execution, privilege escalation, data corruption, or denial of service.
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Description OSIDB Bzimport 2026-06-24 20:02:28 UTC 
py7zr is a Python-based library and utility to support 7zip archive compression, decompression, encryption and decryption. Versions 1.1.2 and below contain an an arbitrary file write vulnerability, which allows symbolic links to be recreated outside the destination directory via crafted malicious symbolic link chains. When using extractall to extract an archive, the library restores these symbolic links, linking them to arbitrary directories on the host file system. During extraction, the program only checks the link arcname within the destination directory, but ignores the combined symlink path resolution. Attackers can exploit this vulnerability by constructing malicious archives, thereby bypassing the directory boundary restrictions implemented by the extractor. Subsequent extraction of regular files through these symbolic links can result in arbitrary file writes. This vulnerability may lead to remote code execution, privilege escalation, data corruption, or denial of service. This issue has been fixed in version 1.1.3.