CVE-2021-29481: Client side sessions should not allow unencrypted storage

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-06-29 · updated 2026-06-17
Weakness: CWE-312

Description

Ratpack is a toolkit for creating web applications. In versions prior to 1.9.0, 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. 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. As of version 1.9.0, a securely randomly generated signing key is used. As a workaround, one may supply an encryption key, as per the documentation recommendation.

Affected products

ratpack: before 1.9.0 — fixed in 1.9.0

How to fix

Upgrade to a fixed version: ratpack 1.9.0. Check the vendor advisory for mitigations.

References

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