CVE-2026-18477

CVE Details

Release Date:	2026-08-03
Impact:	Moderate	What is this?

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.

See more information about CVE-2026-18477 from MITRE CVE dictionary and NIST NVD

NOTE: The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 metrics

Base Score:	4.4
Vector String:	CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N
Version:	3.1
Attack Vector:	Local
Attack Complexity:	High
Privileges Required:	Low
User Interaction:	Required
Scope:	Unchanged
Confidentiality Impact:	None
Integrity Impact:	High
Availability Impact:	None

Errata information

Platform	Errata	Release Date
Oracle Linux version 9 (tar)	ELSA-2026-61581-0	2026-09-01