GHSA-7xx3-m584-x994 A poorly-behaved client could use keepalive requests to monopolize Puma's reactor and create a denial of service attack

• RubyGems puma: < 3.12.2 → fixed in 3.12.2 • RubyGems puma: >= 4.0.0, < 4.3.1 → fixed in 4.3.1

Keepalive thread overload/DoS Impact A poorly-behaved client could use keepalive requests to monopolize Puma's reactor and create a denial of service attack. If more keepalive connections to Puma are opened than there are threads available, additional connections will wait permanently if the attacker sends requests frequently enough. Patches This vulnerability is patched in Puma 4.3.1 and 3.12.2. Workarounds Reverse proxies in front of Puma could be configured to always allow less than X keepalive connections to a Puma cluster or process, where X is the number of threads configured in Puma's thread pool. For more information If you have any questions or comments about this advisory: • Open an issue at puma.