Vulnerability · Published Jun 24, 2026 · Assigned by GitHub_M
CVE-2026-23879py7zr: Arbitrary File Write Vulnerability
High 8.0
In plain English
A high-severity security flaw in py7zr from miurahr. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | py7zr | no fix listed | DEBIAN-CVE-2026-23879 |
| Debian:13 | py7zr | no fix listed | DEBIAN-CVE-2026-23879 |
| Debian:14 | py7zr | 1.1.2+dfsg-1 | DEBIAN-CVE-2026-23879 |
| PyPI | py7zr | 1.1.3 | GHSA-q6rc-2cgv-63h7 |
| PyPI | py7zr | 1.1.3 | PYSEC-2026-2974 |
| Ubuntu:22.04:LTS | py7zr | no fix listed | UBUNTU-CVE-2026-23879 |
| Ubuntu:24.04:LTS | py7zr | no fix listed | UBUNTU-CVE-2026-23879 |
| Ubuntu:25.10 | py7zr | no fix listed | UBUNTU-CVE-2026-23879 |
| Ubuntu:26.04:LTS | py7zr | no fix listed | UBUNTU-CVE-2026-23879 |
| Ubuntu:26.10 | py7zr | no fix listed | UBUNTU-CVE-2026-23879 |
Affected products (as reported)
Weakness: CWE-59 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
References
- https://github.com/miurahr/py7zr/security/advisories/GHSA-q6rc-2cgv-63h7 x_refsource_CONFIRM
- https://github.com/miurahr/py7zr/releases/tag/v1.1.3 x_refsource_MISC