CVE-2025-46336: Rack session gets restored after deletion
First published: Thu May 08 2025(Updated: )
## 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](https://github.com/rack/rack-session/blob/v2.1.0/lib/rack/session/abstract/id.rb#L271-L278) 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-session`, or - Ensure your application invalidates sessions atomically by marking them as logged out e.g., using a `logged_out` 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 This code was previously part of `rack` in Rack < 3, see <https://github.com/rack/rack/security/advisories/GHSA-vpfw-47h7-xj4g> for the equivalent advisory in `rack` (affecting Rack < 3 only).
Credit: security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| rubygems/rack-session | >=2.0.0<2.1.1 | 2.1.1 |
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Reference Links
- https://github.com/rack/rack-session/security/advisories/GHSA-9j94-67jr-4cqj
- https://github.com/rack/rack/security/advisories/GHSA-vpfw-47h7-xj4g
- https://github.com/rack/rack-session/commit/c28c4a8c1861d814e09f2ae48264ac4c40be2d3b
- https://nvd.nist.gov/vuln/detail/CVE-2025-46336
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rack-session/CVE-2025-46336.yml
- https://github.com/advisories/GHSA-9j94-67jr-4cqj (Advisory)
Frequently Asked Questions
What is the severity of CVE-2025-46336?
CVE-2025-46336 is considered a high severity vulnerability due to its potential to allow unauthorized session access.
How do I fix CVE-2025-46336?
To fix CVE-2025-46336, upgrade the Rack::Session::Pool middleware to version 2.1.1 or later.
What systems are affected by CVE-2025-46336?
CVE-2025-46336 affects Rack::Session versions from 2.0.0 up to 2.1.1.
Can CVE-2025-46336 be exploited remotely?
Yes, CVE-2025-46336 can be exploited remotely by unauthenticated users who send simultaneous requests.
What are the consequences of CVE-2025-46336?
The consequences of CVE-2025-46336 include the potential for unauthorized access to user sessions, leading to data breaches.
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