CVE-2026-23879
HighCVSS 8.0Exploitation Probability (EPSS)
Low risk32th percentile - higher than 32% of all known CVEs
Summary
The py7zr library, used for compressing and decompressing 7zip archives, contains an arbitrary file write vulnerability in versions 1.1.2 and below. This allows attackers to create malicious archives that can restore symbolic links to arbitrary directories in the file system.
Risk Assessment
This vulnerability may lead to remote code execution, privilege escalation, data corruption, or denial of service, posing a serious security threat to the organization.
Recommendation
It is recommended to update the py7zr library to version 1.1.3 or later to mitigate this vulnerability.
Other vulnerabilities in py7zr
See all- CVE-2026-55206High
The py7zr library prior to version 1.1.3 contains a denial-of-service vulnerability causing excessive CPU consumption during SevenZipFile initialization. The PackInfo._read() function in archiveinfo.py uses an O(n^2) cumulative sum pattern for attacker-controlled numstreams values parsed from archive headers, allowing a crafted .7z archive to trigger CPU exhaustion.
- CVE-2026-55195High
The py7zr library before version 1.1.3 does not track the total decompressed size, allowing a decompression bomb attack. A crafted .7z file (e.g., 15.6 KB) can expand to 100 MB, exhausting disk space or memory.
Original NVD description (English source)
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.