CVE-2026-41991
Description
A flaw was found in the gzexe utility of GNU gzip. When the mktemp utility is not available, gzexe creates temporary files with predictable names based on the process ID. A local attacker can exploit this by pre-creating a symbolic link to an arbitrary file at the predicted temporary file path. This can lead to a Time-of-Check to Time-of-Use (TOCTOU) condition, allowing the attacker to overwrite arbitrary files on the system.
Statement
A flaw was found in the gzexe utility of GNU gzip. When the mktemp utility is not available in the user's PATH, gzexe creates temporary files with predictable names based on the process ID. A local attacker can exploit this by creating a symbolic link at the predicted temporary file path, leading to a TOCTOU race condition that allows arbitrary file overwrite. On Red Hat Enterprise Linux, mktemp is provided by coreutils which is always installed, making the vulnerable fallback code path effectively unreachable in standard deployments.
Mitigation
Ensure that the mktemp utility (provided by the coreutils package) is available in PATH when using the gzexe utility. On Red Hat Enterprise Linux, mktemp is installed by default and no additional action is needed.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6 | 4.7 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | Required | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | High | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
Understanding the Weakness (CWE)
Confidentiality,Integrity,Access Control
Technical Impact: Read Files or Directories; Modify Files or Directories; Bypass Protection Mechanism
An attacker may be able to traverse the file system to unintended locations and read or overwrite the contents of unexpected files. If the files are used for a security mechanism then an attacker may be able to bypass the mechanism.
Other
Technical Impact: Execute Unauthorized Code or Commands
Windows simple shortcuts, sometimes referred to as soft links, can be exploited remotely since a ".LNK" file can be uploaded like a normal file. This can enable remote execution.
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