Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) in Ratpack

io.ratpack:ratpack-session Updated 02 Oct 2025

Summary

14/05/2019

Disclosed on

CVE-2019-11808

CVE

Yes i

Fix available

Low

Severity

3.7

CVSS Score

CVE-2019-11808: Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) in Ratpack. Affects io.ratpack:ratpack-session versions < 1.6.1. Fixed in 1.6.1. How to fix ↓

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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.