Ubuntu Security Notices USN-8624-1 USN-8624-1: Sinatra vulnerability Publication date 29 July 2026 Overview Sinatra could be made to crash if it received specially crafted network traffic. Releases 22.04 LTS 20.04 LTS 18.04 LTS 16.04 LTS Open side navigation Close side navigation Packages Details Update instructions References Packages ruby-sinatra - Ruby web-development dressed in a DSL Details It was discovered that Sinatra did not properly handle header parsing, causing ETag generation to hang when given specific input. A remote attacker could possibly use this issue to cause a denial of service. It was discovered that Sinatra did not properly handle header parsing, causing ETag generation to hang when given specific input. A remote attacker could possibly use this issue to cause a denial of service. Update instructions After a standard system update you need to restart any applications that use ruby-sinatra to 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 22.04 LTS jammy ruby-sinatra – 2.0.8.1-2+deb11u1ubuntu0.1~esm1 Ubuntu Pro Fix available with Ubuntu Pro via ESM Apps. A community fix might become publicly available in the future. 20.04 LTS focal ruby-sinatra – 2.0.8.1-1ubuntu0.1~esm3 Ubuntu Pro Fix available with Ubuntu Pro via ESM Apps. A community fix might become publicly available in the future. 18.04 LTS bionic ruby-sinatra – 1.4.8-1ubuntu0.1~esm3 Ubuntu Pro Fix available with Ubuntu Pro via ESM Apps. A community fix might become publicly available in the future. 16.04 LTS xenial ruby-sinatra – 1.4.7-3ubuntu0.1~esm3 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-2025-61921 CVE-2025-61921