CVE-2026-41991 Predictable Temporary File in GNU gzip

Low 2.0 Published 29 Jun 2026 Updated 29 Jun 2026

Local attackers can overwrite arbitrary files via symlink attacks in gzexe when mktemp is unavailable, requiring a patch to prevent data modification.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2026-41991?

CVE-2026-41991 is a low-severity path traversal vulnerability in GNU gzip, published on 29 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

Official 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

Weakness: CWE-377

Which versions are affected by CVE-2026-41991?

It affects 1 product.

Linux distribution packages (24)

`gzip` Red Hat:hummingbird:1	All versions	`0:1.14-2.2.hum1`
`gzip` SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise Micro 5.3	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise Micro 5.4	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise Micro 5.5	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise Module for Basesystem 15 SP7	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise Server 12 SP5-LTSS	All versions	`1.10-4.17.1`
`gzip` SUSE:Linux Enterprise Server 15 SP4-LTSS	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise Server 15 SP5-LTSS	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise Server 15 SP6-LTSS	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise Server 16.0	All versions	`1.13-160000.3.1`
`gzip` SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5	All versions	`1.10-4.17.1`
`gzip` SUSE:Linux Enterprise Server for SAP Applications 15 SP4	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise Server for SAP Applications 15 SP5	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise Server for SAP Applications 15 SP6	All versions	`1.10-150200.13.1`
`gzip` SUSE:Linux Enterprise Server for SAP applications 16.0	All versions	`1.13-160000.3.1`
`gzip` SUSE:Linux Micro 6.0	All versions	`1.13-2.1`
`gzip` SUSE:Linux Micro 6.1	All versions	`1.13-slfo.1.1_3.1`
`gzip` SUSE:Linux Micro 6.2	All versions	`1.13-160000.3.1`
`gzip` openSUSE:Leap 16.0	All versions	`1.13-160000.3.1`
`gzip` openSUSE:Tumbleweed	All versions	`1.14-2.1`

Products include Gnu Gzip.

How do I fix CVE-2026-41991?

Apply the vendor's patch.

Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.

Is CVE-2026-41991 being exploited?

There is no known exploitation of CVE-2026-41991 in the wild and no public exploit code.

Sources

Also known as CLSA-2026-1783514299, CLSA-2026-1783934943, DEBIAN-CVE-2026-41991, ECHO-233f-78f2-a73b, GHSA-67v8-88jf-4x6q, JLSEC-2026-1264 and 12 more.