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CVE-2026-41991— Predictable Temporary File in GNU gzip

Quick assessment

Affected
GNU gzip
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

GNU gzip是美国GNU基金会开源的一个文件压缩解压程序。 gzip 1.14及之前版本存在资源管理错误漏洞，该漏洞源于gzexe实用程序中不安全的临时文件处理。当用户PATH中不可用mktemp实用程序时，gzexe会回退到仅基于进程ID（PID）构建临时文件路径，且没有进行排他访问或存在性检查。本地攻击者可预先创建预测的临时文件路径作为指向攻击者可写任意文件的符号链接，当gzexe运行时跟随符号链接覆盖目标文件，导致检查时间与使用时间（TOCTOU）条件，从而允许任意文件覆盖。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.14% · P3

Affected Version Matrix 1

VendorProduct Version RangeStatus
GNU gzip ≤ 1.14 affected
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I. Basic Information for CVE-2026-41991

Vulnerability Information
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Vulnerability Title
Predictable Temporary File in GNU gzip
Source: CVE Program / CVE List V5
Vulnerability 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
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
不安全的临时文件
Source: CVE Program / CVE List V5
Vulnerability Title
GNU gzip 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
GNU gzip是美国GNU基金会开源的一个文件压缩解压程序。 gzip 1.14及之前版本存在资源管理错误漏洞，该漏洞源于gzexe实用程序中不安全的临时文件处理。当用户PATH中不可用mktemp实用程序时，gzexe会回退到仅基于进程ID（PID）构建临时文件路径，且没有进行排他访问或存在性检查。本地攻击者可预先创建预测的临时文件路径作为指向攻击者可写任意文件的符号链接，当gzexe运行时跟随符号链接覆盖目标文件，导致检查时间与使用时间（TOCTOU）条件，从而允许任意文件覆盖。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
GNU gzip 0 ~ 1.14 -

II. Public POCs for CVE-2026-41991

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III. Intelligence Information for CVE-2026-41991

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Patches & Fixes for CVE-2026-41991 (1)

Security Blog Posts for CVE-2026-41991 (1)

IV. Related Vulnerabilities

Same product: gzip
Same vendor: GNU
Same weakness: CWE-377

V. Comments for CVE-2026-41991

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