CVE-2026-41991

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

CVSS v3.1 Score

4.7

MEDIUM

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

EPSS — Exploit Prediction

0.0011

Probability of exploitation

0.01%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-377 CWE-377

Affected Products

Vendor	Product	Versions
gnu	gzip	< 1.14

References

Advisories & Patches

https://cgit.git.savannah.gnu.org/cgit/gzip.git/commit/?id=4e6f8b24ab823146ab8776f0b7fe486ab34d4269

Other References

https://cert.pl/en/posts/2026/04/CVE-2026-41991/ https://www.gnu.org/software/gzip/

Frequently Asked Questions

What is CVE-2026-41991? +

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 It has a CVSS v3.1 base score of 4.7 (MEDIUM).

How severe is CVE-2026-41991? +

CVE-2026-41991 has a CVSS v3.1 score of 4.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0011, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-41991? +

CVE-2026-41991 affects products from gnu, specifically: gzip. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-41991? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2024-49506

Insecure creation of temporary files allows local users on systems with non-default configurations to cause denial of service or set …

CVE-2024-6654

Products for macOS enables a user logged on to the system to perform a denial-of-service attack, which could be misused …

CVE-2025-14307 8.1

An insecure temporary file creation vulnerability exists in the AutoExtract component of Robocode version 1.9.3.6. The createTempFile method fails to …

CVE-2025-46369 7.8

Dell Alienware Command Center 6.x (AWCC), versions prior to 6.10.15.0, contains an Insecure Temporary File vulnerability. A low privileged attacker …

CVE-2025-34194 7.8

Vasion Print (formerly PrinterLogic) Virtual Appliance Host versions prior to 25.1.102 and Application versions prior to 25.1.1413 (Windows client deployments) …

CVE-2025-7707 7.8

The llama_index library version 0.12.33 sets the NLTK data directory to a subdirectory of the codebase by default, which is …