CVE-2026-18477
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.
Impact & exploitability
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N
Affected products we track (2)
Recommendation
Apply the vendor fix in your normal patch cycle. Open any affected product above for its exact safe version.