USN-8733-2: Gzip vulnerabilities
Ubuntu patches Gzip vulnerabilities (CVE-2026-41991) in USN-8733-2 for LTS versions, addressing insecure temp files and incorrect handling of compressed files.
Ubuntu has issued a security notice, USN-8733-2, to address vulnerabilities in the Gzip package for Ubuntu 14.04, 18.04, and 20.04 LTS versions. The update includes fixes for an insecure temporary file creation vulnerability (CVE-2026-41991) that could allow local attackers to overwrite arbitrary files, and other issues that could lead to information disclosure or denial of service. This advisory provides the corresponding fix for the original USN-8733-1 notice.
- Ubuntu has released a security notice (USN-8733-2) to patch Gzip vulnerabilities on Ubuntu 14.04 LTS, 18.04 LTS, and 20.04 LTS.
- The vulnerabilities include insecure temporary file creation in gzexe (CVE-2026-41991) and incorrect handling of compressed files.
- The flaws could lead to local file overwriting, information disclosure, or denial of service.
- This is a follow-up advisory to an initial fix in USN-8733-1.
Vulnerabilities mentionedAll →
- CVE-2026-419912.0<1%GNU gzip contains a vulnerability in the gzexe utility related to insecure temporary file handlingpublished · gnu gzip
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2026-41991 | GNU gzip contains a vulnerability in the gzexe utility related to insecure temporary file handling 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 |
USN-8733-1 fixed vulnerabilities in Gzip. This update provides the corresponding fix for Gzip on Ubuntu 14.04 LTS, Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. Original advisory details: Michał Majchrowicz and Marcin Wyczechowski discovered that Gzip's gzexe utility created temporary files in an insecure manner when mktemp was unavailable. A local attacker could possibly use this issue to overwrite arbitrary files. (CVE-2026-41991) Elias Hasas, Michał Majchrowicz and Marcin Wyczechowski discovered that Gzip incorrectly handled certain compressed files. An attacker could possibly use this issue to obtain sensitive information or cause Gzip to crash, resulting in a denial of service.…
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