How severe is CVE-2026-41991?

CVE-2026-41991 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2026-41991 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-41991?

CVE-2026-41991 affects Gnu Gzip. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-41991?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-41991 published?

CVE-2026-41991 was published on 2026-06-29 and last updated on 2026-07-01.

CVE-2026-41991

CVE-2026-41991 is a medium-severity vulnerability in Gnu Gzip with a CVSS 3.x base score of 4.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-377.

Key facts

Severity: Medium (CVSS 3.x base score 4.7)
CVSS v4: 2.0
EPSS exploit prediction: 0% (1st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-377
Affected product: Gnu Gzip
Published: 2026-06-29
Last modified: 2026-07-01

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

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
How severe is CVE-2026-41991?: CVE-2026-41991 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2026-41991 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-41991?: CVE-2026-41991 affects Gnu Gzip. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-41991?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-41991 published?: CVE-2026-41991 was published on 2026-06-29 and last updated on 2026-07-01.

References

Affected products (1)

cpe:2.3:a:gnu:gzip:*:*:*:*:*:*:*:*

More vulnerabilities in Gnu Gzip

CVE-2004-0603 — Critical (CVSS 10.0): gzexe in gzip 1.3.3 and earlier will execute an argument when the creation of a temp file fails instead of exiting the…
CVE-2022-1271 — High (CVSS 8.8): An arbitrary file write vulnerability was found in GNU gzip's zgrep utility. When zgrep is applied on the attacker's…
CVE-2026-41992 — High (CVSS 7.5): GNU gzip contains a global buffer overflow vulnerability in the LZH decompression logic caused by improper reuse of…
CVE-2001-1228 — High (CVSS 7.5): Buffer overflows in gzip 1.3x, 1.2.4, and other versions might allow attackers to execute code via a long file name,…
CVE-2010-0001 — Medium (CVSS 6.8): Integer underflow in the unlzw function in unlzw.c in gzip before 1.4 on 64-bit platforms, as used in ncompress and…
CVE-2009-2624 — Medium (CVSS 6.8): The huft_build function in inflate.c in gzip before 1.3.13 creates a hufts (aka huffman) table that is too small, which…

All CVEs affecting Gnu Gzip →

Other CWE-377 (Insecure Temporary File) vulnerabilities

CVE-2011-4119 — Critical (CVSS 9.8): caml-light <= 0.75 uses mktemp() insecurely, and also does unsafe things in /tmp during make install.
CVE-2012-2666 — Critical (CVSS 9.8): golang/go in 1.0.2 fixes all.bash on shared machines. dotest() in src/pkg/debug/gosym/pclntab_test.go creates a…
CVE-2015-5224 — Critical (CVSS 9.8): The mkostemp function in login-utils in util-linux when used incorrectly allows remote attackers to cause file name…
CVE-2025-14307 — High (CVSS 8.1): An insecure temporary file creation vulnerability exists in the AutoExtract component of Robocode version 1.9.3.6. The…
CVE-2023-43498 — High (CVSS 8.1): In Jenkins 2.423 and earlier, LTS 2.414.1 and earlier, processing file uploads using MultipartFormDataParser creates…
CVE-2025-46369 — High (CVSS 7.8): Dell Alienware Command Center 6.x (AWCC), versions prior to 6.10.15.0, contains an Insecure Temporary File…

Browse all CWE-377 (Insecure Temporary File) vulnerabilities →