CVE-2019-11808
Ratpack versions before 1.6.1 generate a session ID using a cryptographically weak PRNG in the JDK’s ThreadLocalRandom. This means that if an attacker can determine a small window for the server start time and obtain a session ID value, they can theoretically determine the sequence of session IDs.
Date published : 2019-05-07
https://github.com/ratpack/ratpack/commit/f2b63eb82dd71194319fd3945f5edf29b8f3a42d