py7zr — security advisory
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.
- Products
- py7zr
- Affected versions
- 0.11.3+dfsg-1, 0.11.3+dfsg-1ubuntu1, 0.11.3+dfsg-2, 0.11.3+dfsg-3, 0.11.3+dfsg-4, 0.11.3+dfsg-4ubuntu0.1, 0.11.3+dfsg-6, 0.11.3+dfsg-7, 0.11.3+dfsg-8, 0.11.3+dfsg-8build1, 0.22.0+dfsg-1, 1.0.0+dfsg1-1, 1.0.0+dfsg1-3, 1.0.0+dfsg1-4, 1.0.0+dfsg1-5, 1.1.2+dfsg-1, 1.1.2-1+really1.1.0+dfsg-2, 1.1.3+dfsg-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-23879
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:58 UTC · Revision 1
Source evidence
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.
osv:UBUNTU-CVE-2026-23879
py7zr
Fixed versions: Not specified
py7zr
Fixed versions: Not specified
py7zr
Fixed versions: Not specified
py7zr
Fixed versions: Not specified
py7zr
Fixed versions: Not specified
Complete source record
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"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-23879",
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"summary": "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.",
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"modified": "2026-10-17T12:59:56.181271662Z",
"provider": "osv",
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"references": [
"https://ubuntu.com/security/CVE-2026-23879",
"https://www.cve.org/CVERecord?id=CVE-2026-23879",
"https://github.com/miurahr/py7zr/releases/tag/v1.1.3",
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"published_at": "2026-06-24T20:16:00+00:00"
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