CVE-2019-11808 is a low-severity (CVSS 3.7) CWE-338 vulnerability in io.ratpack:ratpack-session. A fix is available for io.ratpack:ratpack-session — see the affected versions and patch details below.
Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) in Ratpack
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2019-11808 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
io.ratpack:ratpack-session☕io.ratpack:ratpack-java☕io.ratpack:ratpack-groovyReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.ratpack:ratpack-session | all versions | 1.6.1io.ratpack:ratpack-session:1.6.1 |
| ☕Maven | io.ratpack:ratpack-java | all versions | 1.6.1io.ratpack:ratpack-java:1.6.1 |
| ☕Maven | io.ratpack:ratpack-groovy | all versions | 1.6.1io.ratpack:ratpack-groovy:1.6.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.ratpack:ratpack-session, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.ratpack:ratpack-session to 1.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-11808 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2019-11808 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2019-11808. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2019-11808 in your dependencies?
O3 Security finds CVE-2019-11808 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.