# CVE-2026-18477: Tar: tar: toctou in incremental dumpdir 'x' rename handling allows restore path escape

CVE-2026-18477 is fixed in tar on 1 platform, first by RHSA-2026:61586, released July 31, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-18477
- Priority: Routine
- CVSS: 5.6 (Moderate)
- EPSS: 0.0010
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 31, 2026
- Weakness: Time-of-check Time-of-use (TOCTOU) Race Condition
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-18477

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | tar RHEL 10 | 1.35-13.el10_2 | [RHSA-2026:61586](https://patchblox.com/security/data/fix/linux/rhsa-2026-61586.md) | Jul 31, 2026 |
| Linux | tar RHEL 8 | 2:1.30-13.el8_10 | [RHSA-2026:70390](https://patchblox.com/security/data/fix/linux/rhsa-2026-70390.md) | Sep 23, 2026 |
| Linux | tar RHEL 9 | 2:1.34-13.el9_8 | [RHSA-2026:61581](https://patchblox.com/security/data/fix/linux/rhsa-2026-61581.md) | Sep 13, 2026 |
| Linux | tar almalinux 10 | 2:1.35-13.el10_2 | [ALSA-2026:61586](https://patchblox.com/security/data/fix/linux/alsa-2026-61586.md) | Aug 31, 2026 |
| Linux | tar almalinux 8 | 2:1.30-13.el8_10 | [ALSA-2026:70390](https://patchblox.com/security/data/fix/linux/alsa-2026-70390.md) | Sep 22, 2026 |
| Linux | tar almalinux 9 | 2:1.34-13.el9_8 | [ALSA-2026:61581](https://patchblox.com/security/data/fix/linux/alsa-2026-61581.md) | Aug 31, 2026 |
| Linux | tar ol 10 | 2:1.35-13.el10_2 | [ELSA-2026-61586-0](https://patchblox.com/security/data/fix/linux/elsa-2026-61586-0.md) | Sep 1, 2026 |
| Linux | tar ol 8 | 2:1.30-13.el8_10 | [ELSA-2026-70390](https://patchblox.com/security/data/fix/linux/elsa-2026-70390.md) | Sep 23, 2026 |
| Linux | tar ol 9 | 2:1.34-13.el9_8 | [ELSA-2026-61581-0](https://patchblox.com/security/data/fix/linux/elsa-2026-61581-0.md) | Sep 1, 2026 |
| Linux | tar rocky 10 | 2:1.35-13.el10_2 | [RLSA-2026:61586](https://patchblox.com/security/data/fix/linux/rlsa-2026-61586.md) | Sep 11, 2026 |
| Linux | tar rocky 8 | 2:1.30-13.el8_10 | [RLSA-2026:70390](https://patchblox.com/security/data/fix/linux/rlsa-2026-70390.md) | Sep 24, 2026 |
| Linux | tar rocky 9 | 2:1.34-13.el9_8 | [RLSA-2026:61581](https://patchblox.com/security/data/fix/linux/rlsa-2026-61581.md) | Sep 1, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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