Predictable Temporary File in GNU gzip_CVE-2026-41991

2 / 10

LOW

CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

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

Basic Information

ID CVE-2026-41991

Source CERT-PL

Published Jun 29, 2026 at 10:15

Affected Product

Vendor GNU

Product gzip

Affected Versions GNU gzip 0

CWE Classification

CWE-377

References

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    "published": "2026-06-29T10:15:50.766Z",
    "modified": "2026-06-29T10:15:50.766Z",
    "type": "cve",
    "title": "Predictable Temporary File in GNU gzip",
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    "references": "https://cert.pl/en/posts/2026/04/CVE-2026-41991/\nhttps://www.gnu.org/software/gzip/\nhttps://cgit.git.savannah.gnu.org/cgit/gzip.git/commit/?id=4e6f8b24ab823146ab8776f0b7fe486ab34d4269",
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