UBUNTU-CVE-2026-41991

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UBUNTU-CVE-2026-41991

Summary:

Details: 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

References: https://ubuntu.com/security/CVE-2026-41991, https://www.cve.org/CVERecord?id=CVE-2026-41991, https://cert.pl/en/posts/2026/04/CVE-2026-41991/, https://www.gnu.org/software/gzip/, https://ubuntu.com/security/notices/USN-8512-1, https://ubuntu.com/security/notices/USN-8733-1, https://ubuntu.com/security/notices/USN-8733-2