CVE-2026-23879: py7zr is a Python-based library and utility to support 7zip archive compression, decompression, encryption and decryption. Versions 1.1.2 and below co...

Description

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.

Metrics

CVSS 3.1

8/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

EPSS Probability

0.40%

32.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-59

References

Timeline

Published: Jun 24, 2026
Last Modified: Jun 25, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-23879?

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.

How severe is CVE-2026-23879?

CVE-2026-23879 has a CVSS score of 8/10 (HIGH severity). The EPSS model estimates a 0.40% probability of exploitation in the next 30 days.

How do I fix CVE-2026-23879?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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