CVE-2026-41991: gnu gzip Insecure Temporary File

Vulnerability summary

CVE-2026-41991 is a medium (CVSS 4.7) Insecure Temporary File vulnerability in gnu gzip. EPSS estimates a 0.12% chance of exploitation in the next 30 days, higher than 1.5% of scored vulnerabilities.

Timeline

1. 29-06-2026
   PublishedVulnerability first disclosed.
2. 29-06-2026
   Last modifiedVulnerability information updated.

Description

GNU gzip contains a vulnerability in the gzexe utility related to insecure temporary file handling. When the mktemp utility is not available in the user’s PATH, gzexe falls back to constructing a temporary file path based solely on the process ID (PID). This predictable filename is created without exclusive access or existence checks. A local attacker can pre‑create the predicted temporary file path as a symbolic link pointing to an arbitrary file writable by the victim. When gzexe runs, it follows the symlink and overwrites the target file, resulting in a time‑of‑check to time‑of‑use (TOCTOU) condition that allows arbitrary file overwrite. This issue has been fixed in the commit 4e6f8b24ab823146ab8776f0b7fe486ab34d4269

• CWE-377Insecure Temporary FileCreating and using insecure temporary files can leave application and system data vulnerable to attack.