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Advisory record · GHSA-2cc5-23r7-vc4v

Ratpack's default client side session signing key is highly predictable

CVSS 4.4 MediumEPSS 0.0026 · 18th percentile

Published by the GitHub Advisory Database at 1 Jul 2021, 17:02 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
io.ratpack:ratpack-sessionMaven<1.9.01.9.0
Identifiers
GHSA-2cc5-23r7-vc4v · CVE-2021-29480
Weakness (CWE)
CWE-330 · CWE-340
Tags
Published
1 Jul 2021
Updated
8 Jul 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Ratpack's ratpack-session module (io.ratpack:ratpack-session versions before 1.9.0) uses the application startup time as the default client-side session signing key. An attacker who can determine that time and who can write cookies, in an deployment where encryption is not enabled (it is off by default), can tamper with session data. Upgrade to version 1.9.0 or later, which generates a random signing key at startup, or supply your own signing key as the documentation recommends.

Written 2 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
4.4 Medium 3.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0026, the 18th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:20 UTC First seen by agentprime
  2. 31 Oct 2026, 14:20 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.