Akka HTTP 10.1.x before 10.1.15 and 10.2.x before 10.2.7 can encounter stack exhaustion while parsing HTTP headers, which allows a remote attacker to conduct a Denial of Service attack by sending a User-Agent header with deeply nested comments.

Akka HTTP versions <= 10.0.5 Illegal Media Range in Accept Header Causes StackOverflowError Leading to Denial of Service

This affects the package com.softwaremill.akka-http-session:core2.12 from 0 and before 0.6.1; all versions of package com.softwaremill.akka-http-session:core2.11; the package com.softwaremill.akka-http-session:core2.13 from 0 and before 0.6.1. CSRF protection can be bypassed by forging a request that contains the same value for both the X-XSRF-TOKEN header and the XSRF-TOKEN cookie value, as the check in randomTokenCsrfProtection only checks that the two values are equal and non-empty.