# CVE-2026-11623: tmux image.c image_free use after free

CVE-2026-11623 is fixed in tmux on 1 platform, first by tmux 3.6a-2ubuntu0.1, released June 8, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-11623
- Priority: Routine
- CVSS: 4.5 (Low)
- EPSS: 0.0012
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 8, 2026
- Weakness: Use After Free
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-11623

## Description

A security vulnerability has been detected in tmux up to 3.6a. Affected is the function image_free of the file image.c. Such manipulation leads to use after free. Local access is required to approach this attack. This attack is characterized by high complexity. The exploitability is told to be difficult. The exploit has been disclosed publicly and may be used. Upgrading to version 3.7-rc is able to address this issue. The name of the patch is fc6d94a9f8a593bd8b7031650802084385d4ee03. The affected component should be upgraded.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | tmux Debian 14 | 3.6b-1 | [DEBIAN-CVE-2026-11623](https://patchblox.com/security/data/fix/linux/debian-cve-2026-11623.md) | Jun 27, 2026 |
| Linux | tmux Ubuntu 26.04.1 LTS (resolute) | 3.6a-2ubuntu0.1 | [tmux 3.6a-2ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-tmux-3.6a-2ubuntu0.1.md) | Jun 8, 2026 |

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Data as of 2026-11-09T01:18:40Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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