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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

3.7 · CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS

• CVE-2019-11808: 1.31% estimated exploitation activity in the next 30 days; percentile 70.78 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

14 May 2019, 04:01 UTC

Last modified by the source

1 Feb 2023, 05:01 UTC

Source last checked

26 Oct 2026, 16:05 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-54mg-vgrp-mwx9

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# Patch Next advisory brief: CVE-2019-11808

Advisory: Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) in Ratpack
IDs: CVE-2019-11808, GHSA-54mg-vgrp-mwx9
Record: https://patchnext.com/advisories/cve-2019-11808 (revision 1, source checked 26 Oct 2026, 16:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: io.ratpack:ratpack-session 1.6.1; io.ratpack:ratpack-java 1.6.1; io.ratpack:ratpack-groovy 1.6.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven io.ratpack:ratpack-session: affected < 1.6.1; fixed in 1.6.1
- Maven io.ratpack:ratpack-java: affected < 1.6.1; fixed in 1.6.1
- Maven io.ratpack:ratpack-groovy: affected < 1.6.1; fixed in 1.6.1

## Suggested inspection (read-only)
- Maven io.ratpack:ratpack-session: check the installed version with your package manager.
- Maven io.ratpack:ratpack-java: check the installed version with your package manager.
- Maven io.ratpack:ratpack-groovy: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on io.ratpack:ratpack-session, io.ratpack:ratpack-java, io.ratpack:ratpack-groovy.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-54mg-vgrp-mwx9 (GitHub-reviewed advisory GHSA-54mg-vgrp-mwx9 lists affected ranges: Maven io.ratpack:ratpack-session >=0 =0 =0 <1.6.1)

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