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Fencer Vulns
medium 4.4

CVE-2026-18477 json

Tar: tar: toctou in incremental dumpdir 'x' rename handling allows restore path escape

published 2026-08-03 3 mo ago modified 2026-11-05 3 d ago also EUVD-2026-52336 , JLSEC-2026-1344

cvss
4.4
version 3.1, CNA
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

A TOCTOU (Time-of-Check Time-of-Use) vulnerability in GNU tar's incremental dumpdir 'X' rename handling allows a local attacker with write access to a directory being backed up to influence the restore process if the attacker has access to the system where the restore is being performed. During restoration, files or directories may be created, renamed or overwritten outside the intended extraction directory. This could lead to unauthorized file modification or, in some cases, privilege escalation. Exploitation does not require the attacker to modify or craft the archive, and standard backup and restore workflows—including extracting into a newly created directory without using the -P option do not mitigate the issue.

Patch / fix

  • Red Hat Red Hat Enterprise Linux 10 2:1.35-13.el10_2
  • Red Hat Red Hat Enterprise Linux 8 2:1.30-13.el8_10
  • Red Hat Red Hat Enterprise Linux 9 2:1.34-13.el9_8
  • Red Hat Red Hat Discovery 2 1788205779
  • Red Hat Red Hat Hardened Images 1.35-9.1.hum1
  • Red Hat Red Hat Update Infrastructure 5 1788765051, 1788880445, 1788880456, 1788880464, 1788880581
  • tar RHEL 8 2:1.30-13.el8_10
  • tar RHEL 10.2 2:1.35-13.el10_2
  • tar RHEL 9 2:1.34-13.el9_8
  • tar hummingbird 1 1.35-9.1.hum1

red hat advisories RHSA-2026:70390RHSA-2026:61586RHSA-2026:61581RHSA-2026:49361

  • tar AlmaLinux 8 2:1.30-13.el8_10
  • tar AlmaLinux 9 2:1.34-13.el9_8
  • tar AlmaLinux 10 2:1.35-13.el10_2

almalinux advisories ALSA-2026:70390ALSA-2026:61581ALSA-2026:61586

  • tar Rocky Linux 8 2:1.30-13.el8_10
  • tar Rocky Linux 10 2:1.35-13.el10_2
  • tar Rocky Linux 9 2:1.34-13.el9_8

rocky linux advisories RLSA-2026:70390RLSA-2026:61586RLSA-2026:61581

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-2026-18477 updated cvss 4.4

tar: tar: TOCTOU in incremental dumpdir 'X' rename handling allows restore path escape

  • Red Hat Enterprise Linux 6 tar Red Hat Enterprise Linux 7 tar
    affected: workaround, no fix planned “Out of support scope”
  • 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
    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) tar 1.30-13.el8_10
    fixed: vendor fix RHSA-2026:70390
  • Red Hat Enterprise Linux BaseOS (v. 9) tar 1.34-13.el9_8
    fixed: vendor fix RHSA-2026:61581
  • Red Hat Enterprise Linux BaseOS (v. 10) tar 1.35-13.el10_2
    fixed: vendor fix RHSA-2026:61586
  • Red Hat Hardened Images tar 1.35-9.1.hum1
    fixed: vendor fix RHSA-2026:49361
  • 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
show 1 more
  • Red Hat Discovery 2 discovery/discovery-ui-rhel9 1788206196 Red Hat Hardened Images rust 1.97.1-2.hum1, chunkah 0.6.0-3.hum1, netavark 2.0.0-3.hum1, nodejs26 26.5.1-1.5.hum1, aardvark-dns 2.0.0-2.hum1, yarnpkg 1.22.22-18.1.hum1, +4 more
    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
3 mo ago

Exploit prediction

0.10% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.4 CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N
OSV 3.1 4.4 CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
julia Tar_jll
>=1.35.0+0
 no fix listed

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Discovery 2
  • Red Hat Red Hat Hardened Images
  • Red Hat Red Hat Update Infrastructure 5
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat OpenShift Container Platform 4
  • Red Hat Red Hat OpenShift Container Platform 5

Classification

Weakness
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

References

Sources

Fencer Vulns 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.