Buffer overflow in Tmux
CVE-2026-11623
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.5 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L.
EPSS exploit prediction
EPSS: 0.001 (1.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 2nd percentile — 1.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: 0.000
Affected products
- Tmux — versions 3.6a, 3.7-rc
Weakness classification (CWE)
References
- gist.github.com/XlabAITeam/f0d9952595f795129a3258ba73bbc3cb (exploit)
- github.com/tmux/tmux/ (product)
- github.com/tmux/tmux/commit/fc6d94a9f8a593bd8b7031650802084385d4ee03 (patch)
- github.com/tmux/tmux/releases/tag/3.7-rc (patch)
- vuldb.com/cve/CVE-2026-11623 (third-party-advisory)
- vuldb.com/submit/835623 (third-party-advisory)
- vuldb.com/vuln/369303 (technical-description, vdb-entry)
- vuldb.com/vuln/369303/cti (signature, permissions-required)
Frequently asked questions
- What is CVE-2026-11623?
- CVE-2026-11623 is a medium-severity vulnerability in Tmux, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 4.5/10. Published 2026-06-09.
- How severe is CVE-2026-11623?
- Medium severity. CVSS v3 base score is 4.5 out of 10.