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.
{
"github_reviewed_at": "2019-05-14T03:48:09Z",
"github_reviewed": true,
"nvd_published_at": "2019-05-07T07:29:00Z",
"severity": "LOW",
"cwe_ids": [
"CWE-338"
]
}