Ubuntu Security Notices USN-8343-1 USN-8343-1: multipart vulnerability Publication date 28 May 2026 Overview multipart could be made to use excessive resources if it received specially crafted input. Releases 26.04 LTS 25.10 Open side navigation Close side navigation Packages Details Update instructions References Packages multipart - library for handling multipart/form-data POST requests Details It was discovered that multipart had an ambiguous regular expression alternation when handling certain HTTP header values. A remote attacker could possibly use this issue to cause multipart to use excessive resources, leading to a denial of service. It was discovered that multipart had an ambiguous regular expression alternation when handling certain HTTP header values. A remote attacker could possibly use this issue to cause multipart to use excessive resources, leading to 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 python3-multipart – 1.3.0-3ubuntu0.1 25.10 questing python3-multipart – 1.2.1-2+deb13u1build0.25.10.1 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-2026-28356 CVE-2026-28356