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Fencer Intel
medium 4.7

CVE-2026-41991 json

Predictable Temporary File in GNU gzip

published 4mo ago modified 15d ago also EUVD-2026-40068 , GHSA-67v8-88jf-4x6q , JLSEC-2026-1264

cvss
4.7
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits
0
none known

Summary

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

Patch / fix

  • gzip Debian 13 1.13-1+deb13u1
  • gzip Debian 14 1.14-1

debian advisories DEBIAN-CVE-2026-41991

  • gzip Ubuntu 22.04 LTS 1.10-4ubuntu4.2
  • gzip Ubuntu 24.04 LTS 1.12-1ubuntu3.2
  • gzip Ubuntu 26.04 LTS 1.14-1~exp2ubuntu1.1
  • gzip Ubuntu Pro 14.04 LTS 1.6-3ubuntu1+esm2
  • gzip Ubuntu Pro 16.04 LTS 1.6-4ubuntu1+esm2
  • gzip Ubuntu Pro 18.04 LTS 1.6-5ubuntu1.2+esm1
  • gzip Ubuntu Pro 20.04 LTS 1.10-0ubuntu4.1+esm1

ubuntu advisories UBUNTU-CVE-2026-41991

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • gzip hummingbird 1 1.15-1.hum1
  • gzip RHEL 8 1.9-15.el8_10
  • gzip RHEL 10.2 1.13-4.el10_2
  • gzip RHEL 9 1.12-2.el9_8
  • gzip hummingbird 1 1.14-2.2.hum1

red hat advisories RHSA-2026:79717RHSA-2026:65998RHSA-2026:61625RHSA-2026:61623RHSA-2026:33771

  • gzip SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +11 more 1.10-150200.13.1
  • gzip Linux Micro 6.1 1.13-slfo.1.1_3.1
  • gzip Linux Micro 6.0 1.13-2.1
  • gzip SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 1.13-160000.3.1
  • gzip SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 1.10-4.17.1

suse advisories SUSE-SU-2026:3269-1SUSE-SU-2026:3241-1SUSE-SU-2026:22906-1SUSE-SU-2026:22918-1SUSE-SU-2026:22753-1SUSE-SU-2026:22818-1

  • gzip openSUSE Leap 16.0 1.13-160000.3.1
  • gzip openSUSE Tumbleweed 1.14-2.1

opensuse advisories openSUSE-SU-2026:21371-1openSUSE-SU-2026:11174-1

  • gzip AlmaLinux 8 1.9-15.el8_10
  • gzip AlmaLinux 9 1.12-2.el9_8
  • gzip AlmaLinux 10 1.13-4.el10_2

almalinux advisories ALSA-2026:65998ALSA-2026:61623ALSA-2026:61625

  • gzip Rocky Linux 8 1.9-15.el8_10
  • gzip Rocky Linux 10 1.13-4.el10_2
  • gzip Rocky Linux 9 1.12-2.el9_8

rocky linux advisories RLSA-2026:65998RLSA-2026:61625RLSA-2026:61623

  • gzip Alpine 3.24 1.15-r0

alpine advisories ALPINE-CVE-2026-41991

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2026-41991 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-41991 updated cvss 6.0

gzip: gzip: Arbitrary file overwrite via insecure temporary file handling in gzexe utility

  • Red Hat Enterprise Linux 6 gzip Red Hat Enterprise Linux 7 gzip Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9 Red Hat OpenShift Dev Spaces devspaces/code-sshd-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Discovery 2 discovery/discovery-server-rhel9 1788205779
    fixed: vendor fix RHSA-2026:61783
  • Red Hat Enterprise Linux BaseOS (v. 8) gzip 1.9-15.el8_10
    fixed: vendor fix RHSA-2026:65998
  • Red Hat Enterprise Linux BaseOS (v. 9) gzip 1.12-2.el9_8
    fixed: vendor fix RHSA-2026:61623
  • Red Hat Enterprise Linux BaseOS (v. 10) gzip 1.13-4.el10_2
    fixed: vendor fix RHSA-2026:61625
  • Red Hat Hardened Images gzip 1.15-1.hum1, gzip 1.14-2.2.hum1
    fixed: vendor fix RHSA-2026:33771
  • Red Hat Update Infrastructure 5 rhui5/cds-rhel9 1788880464, rhui5/rhua-rhel9 1788880581, rhui5/haproxy-rhel9 1788880456, rhui5/installer-rhel9 1788765051, rhui5/cds-kubernetes-rhel9 1788880445
    fixed: vendor fix RHSA-2026:66018
  • Red Hat Discovery 2 discovery/discovery-ui-rhel9 1788206196
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4mo ago

Exploit prediction

0.12% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 4.0 2.0 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
CNA 4.0 2.0 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
OSV 3.1 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
julia Gzip_jll
all versions
 no fix listed

Affected products

  • GNU gzip

Classification

Weakness
  • CWE-377 DEPRECATED: Insecure Temporary File

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.