Buffer Overflow in tmux (CVE-2026-11623)
Summary
Vulnerability in tmux (CVE-2026-11623). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-11623 has been found in tmux.
Risk of unauthorized operations or information disclosure. CVSS score: 4.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "tmux CVE-2026-11623" on the vendor's site.
CVE-2026-11623 (tmux) — CWE-119 / CVSS v3 4.5
Attack vector: local / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-119) exists in tmux.
Check the vendor advisory for the affected versions of tmux.
Severity: Medium (CVSS 4.5/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'tmux' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'tmux' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
tmuxを grep し、稼働しているサービス・バージョンを把握する。 -
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-11623 tmux Fixed in: 3.5a-r1
- Debian DEBIAN-CVE-2026-11623 tmux
- Ubuntu UBUNTU-CVE-2026-11623 tmux
References
- advisory vuldb.com
- advisory vuldb.com
- advisory vuldb.com
- advisory nvd.nist.gov
- advisory github.com
- patch github.com
- patch github.com
- report gist.github.com
- report vuldb.com
- web github.com
- web github.com
- web github.com