Summary
Unencrypted storage of client side sessions
Workarounds
Supply an encryption key, as per the documentation recommendation.
References
Impact
The default configuration of client side sessions results in unencrypted, but signed, data being set as cookie values. This means that if something sensitive goes into the session, it could be read by something with access to the cookies.
Note: the documentation does point this out and encourage users to add an encryption key, but it is not mandatory.
For this to be a vulnerability, some kind of sensitive data would need to be stored in the session and the session cookie would have to leak. For example, the cookies are not configured with httpOnly and an adjacent XSS vulnerability within the site allowed capture of the cookies.
The proposed change is to change the default behaviour to use a randomly generated encryption key. This would mean that sessions do not survive app restarts, but this is already the behaviour given the random signing key.
CVE-2021-29481 has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.9.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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As of version 1.9.0, a securely randomly generated signing key is used.
Frequently Asked Questions
- What is CVE-2021-29481? CVE-2021-29481 is a medium-severity security vulnerability in io.ratpack:ratpack-session (maven), affecting versions < 1.9.0. It is fixed in 1.9.0.
- How severe is CVE-2021-29481? CVE-2021-29481 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of io.ratpack:ratpack-session are affected by CVE-2021-29481? io.ratpack:ratpack-session (maven) versions < 1.9.0 is affected.
- Is there a fix for CVE-2021-29481? Yes. CVE-2021-29481 is fixed in 1.9.0. Upgrade to this version or later.
- Is CVE-2021-29481 exploitable, and should I be worried? Whether CVE-2021-29481 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2021-29481 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2021-29481? Upgrade
io.ratpack:ratpack-sessionto 1.9.0 or later.