CVE-2025-32441: Rack session gets restored after deletion
Summary
When using the Rack::Session::Pool middleware, simultaneous rack requests can restore a deleted rack session, which allows the unauthenticated user to occupy that session.
Details
Rack session middleware prepares the session at the beginning of request, then saves is back to the store with possible changes applied by host rack application. This way the session becomes to be a subject of race conditions in general sense over concurrent rack requests.
Impact
When using the Rack::Session::Pool middleware, and provided the attacker can acquire a session cookie (already a major issue), the session may be restored if the attacker can trigger a long running request (within that same session) adjacent to the user logging out, in order to retain illicit access even after a user has attempted to logout.
Mitigation
- Update to the latest version of rack, or - Ensure your application invalidates sessions atomically by marking them as logged out e.g., using a loggedout flag, instead of deleting them, and check this flag on every request to prevent reuse, or - Implement a custom session store that tracks session invalidation timestamps and refuses to accept session data if the session was invalidated after the request began.
Related
As this code was moved to rack-session in Rack 3+, see <https://github.com/rack/rack-session/security/advisories/GHSA-9j94-67jr-4cqj> for the equivalent advisory in rack-session (affecting Rack 3+ only).
Other sources
Rack is a modular Ruby web server interface. Prior to version 2.2.14, when using the Rack::Session::Pool middleware, simultaneous rack requests can restore a deleted rack session, which allows the unauthenticated user to occupy that session. Rack session middleware prepares the session at the beginning of request, then saves is back to the store with possible changes applied by host rack application. This way the session becomes to be a subject of race conditions in general sense over concurrent rack requests. When using the Rack::Session::Pool middleware, and provided the attacker can acquire a session cookie (already a major issue), the session may be restored if the attacker can trigger a long running request (within that same session) adjacent to the user logging out, in order to retain illicit access even after a user has attempted to logout. Version 2.2.14 contains a patch for the issue. Some other mitigations are available. Either ensure the application invalidates sessions atomically by marking them as logged out e.g., using a loggedout flag, instead of deleting them, and check this flag on every request to prevent reuse; or implement a custom session store that tracks session invalidation timestamps and refuses to accept session data if the session was invalidated after the request began.
— MITRE
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2025-32441?
CVE-2025-32441 has a medium severity rating due to the potential for unauthenticated users to access and occupy compromised sessions.
How do I fix CVE-2025-32441?
To fix CVE-2025-32441, upgrade Rack to version 2.2.14 or later.
What are the affected versions for CVE-2025-32441?
CVE-2025-32441 affects Rack versions prior to 2.2.14.
What type of vulnerability is CVE-2025-32441?
CVE-2025-32441 is a session management vulnerability in the Rack::Session::Pool middleware.
Can CVE-2025-32441 be exploited remotely?
Yes, CVE-2025-32441 can be exploited by remote unauthenticated users if the affected session middleware is used.