Asta12

**Name of the Vulnerable Software and Affected Versions** Puma versions prior to 5.5.1 and 4.3.9 **Description** The issue is related to HTTP request smuggling when using Puma with a proxy that forwards HTTP header values containing the LF character. This could allow a client to smuggle a request through a proxy, causing the proxy to send a response back to another unknown client. The only proxy known to have this behavior is Apache Traffic Server. If the proxy uses persistent connections and the client adds another request via HTTP pipelining, the proxy may mistake it as the first request's body. Puma, however, would see it as two requests, and when processing the second request, send back a response that the proxy does not expect. If the proxy has reused the persistent connection to Puma to send another request for a different client, the second response from the first client will be sent to the second client. **Recommendations** To resolve the issue, update to Puma version 5.5.1 or 4.3.9. As a temporary workaround, do not use Apache Traffic Server with Puma. Consider using a proxy that does not forward LF characters as line endings, such as Nginx, Apache (>2.4.25), Haproxy, Caddy, or Traefik.