Ubuntu Security Notices USN-8428-1 USN-8428-1: tmux vulnerability Publication date 15 June 2026 Overview tmux could be made to crash if it received specially crafted input. Releases 26.04 LTS Open side navigation Close side navigation Packages Details Update instructions References Packages tmux - terminal multiplexer Details It was discovered that tmux incorrectly handled image cleanup, leading to a use-after-free vulnerability. A local attacker could possibly use this issue to cause tmux to crash, resulting in a denial of service. It was discovered that tmux incorrectly handled image cleanup, leading to a use-after-free vulnerability. A local attacker could possibly use this issue to cause tmux to crash, resulting in a denial of service. Update instructions In general, a standard system update will make all the necessary changes. Learn more about how to get the fixes. The problem can be corrected by updating your system to the following package versions: Ubuntu Release Package Version 26.04 LTS resolute tmux – 3.6a-2ubuntu0.1 Reduce your security exposure Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines. Get Ubuntu Pro References CVE-2026-11623 CVE-2026-11623