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MEDIUM

CVE-2026-18477

CVSS v3

4.4

MEDIUM

EPSS Score

0.1 %

exploit probability, as of 2026-10-19

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • tarAlmaLinux:10all versions · fixed in 2:1.35-13.el10_2
  • tarAlmaLinux:9all versions · fixed in 2:1.34-13.el9_8
  • tarAlmaLinux:8all versions · fixed in 2:1.30-13.el8_10

Vendor advisories

  • CVE-2026-18477 Red Hat Product Security49 products fixed · 4 known affected

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

    tar.src as a component of Red Hat Enterprise Linux 6 · tar.src as a component of Red Hat Enterprise Linux 7 · openshift/ose-rhel-coreos-8 as a component of Red Hat OpenShift Container Platform 4

  • RHSA-2026:70390 Red Hat Product Security13 products fixed

    Red Hat Security Advisory: tar security, bug fix, and enhancement update

  • RHSA-2026:66018 Red Hat Product Security5 products fixed

    Red Hat Security Advisory: Red Hat Update Infrastructure 5.3 security update

  • RHSA-2026:61586 Red Hat Product Security13 products fixed

    Red Hat Security Advisory: tar security, bug fix, and enhancement update

  • RHSA-2026:61783 Red Hat Product Security2 products fixed

    Red Hat Security Advisory: A Subscription Management tool for finding and reporting Red Hat product usage

  • RHSA-2026:61581 Red Hat Product Security13 products fixed

    Red Hat Security Advisory: tar security, bug fix, and enhancement update

1 more advisory

Full record on NVD

Description

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.

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N
Published
2026-08-03
Last Modified
2026-08-05

Frequently asked questions

What is CVE-2026-18477?

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.

Is CVE-2026-18477 actively exploited?

Active exploitation of CVE-2026-18477 has not been confirmed. Its EPSS score was 0.1% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-18477?

CVE-2026-18477 has a CVSS v3 base score of 4.4 (MEDIUM severity), with vector string CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N.

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