cvedb.io
CVE-2026-39324
CRITICAL · CVSS 9.8
EPSS exploitation probability: 0%
Published 2026-04-07T18:16:43.387 · Last modified 2026-06-17T10:41:55.280

Summary

Rack::Session is a session management implementation for Rack. From 2.0.0 to before 2.1.2, Rack::Session::Cookie incorrectly handles decryption failures when configured with secrets:. If cookie decryption fails, the implementation falls back to a default decoder instead of rejecting the cookie. This allows an unauthenticated attacker to supply a crafted session cookie that is accepted as valid session data without knowledge of any configured secret. Because this mechanism is used to load session state, an attacker can manipulate session contents and potentially gain unauthorized access. This vulnerability is fixed in 2.1.2.

Affected products

rack — rack-session

Does this affect you?

Add your gear to cvedb and we'll alert you only when rack ships something exploited.

Check my exposure →

References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.