🛡️ CVE-2026-18477 on Debian — tar

⚪ Unknown ✅ No Known Exploit OSV

N/A

CVSS Score

0 Low4 Medium7 High9 Critical10

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.

Distribution advisory

This page covers CVE-2026-18477 as tracked by Debian, for the package tar. No fixed version has been recorded for this distribution yet.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is high, an attacker needs low-level privileges on the target. A user must be tricked into taking some action. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity high, availability none.

Weakness class

DEBIAN-CVE-2026-18477 is classified as CWE-367: Time-of-check Time-of-use Race Condition. The state checked and the state acted upon can differ, because it may change between the two steps.

Affected software

DEBIAN-CVE-2026-18477 is recorded against 1 package.

tar

Timeline and source

Published on 3 August 2026 and last revised on 6 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

Details

Severity Unknown

CVSS Score N/A

CVSS Vector CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N

CWE N/A

Public Exploit ✅ No

Source OSV

Published 2026-08-03

Updated 2026-08-11

Modified 2026-08-06

Fix URL N/A

Affected Packages

Software	From version	Fixed in
tar	—	—

References

ADVISORY https://security-tracker.debian.org/tracker/CVE-2026-18477

🔗 NVD 🔗 Mitre

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