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CVE-2026-18477

4.4 · MEDIUM

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 res…

Published Aug 3, 2026CWE-367EPSS 0.08%

Overview

CVE-2026-18477 is a medium-severity vulnerability. It was published on August 3, 2026 and has a CVSS 3.1 base score of 4.4 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 4.4, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refaccess.redhat.com/errata/RHSA-2026:49361Refaccess.redhat.com/security/cve/CVE-2026-18477Refbugzilla.redhat.com/show_bug.cgi?id=2509735

How CyberStrike helps

Frequently asked questions

What is CVE-2026-18477?

CVE-2026-18477 is a medium-severity vulnerability. It was published on August 3, 2026 and has a CVSS 3.1 base score of 4.4 (MEDIUM).

How severe is CVE-2026-18477?

This vulnerability has a CVSS 3.1 base score of 4.4, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-18477?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-18477?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-18477 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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