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.
CVE-2026-18477
CVSS base score
4.4 (v3.1)
Severity
MEDIUM
Attack vector
Local
Weakness
CWE-367
Last modified
October 30, 2026
CVSS vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N
Affected products
gnu tar
redhat openshift container platform
redhat enterprise linux
References
- access.redhat.com Vendor Advisory
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com Vendor Advisory
- bugzilla.redhat.com Issue Tracking, Vendor Advisory