Package Instance

Possible Information Leak / Session Hijack Vulnerability in Rack
There's a possible information leak / session hijack vulnerability in Rack. Attackers may be able to find and hijack sessions by using timing attacks targeting the session id. Session ids are usually stored and indexed in a database that uses some kind of scheme for speeding up lookups of that session id. By carefully measuring the amount of time it takes to look up a session, an attacker may be able to find a valid session id and hijack the session.

The session id itself may be generated randomly, but the way the session is indexed by the backing store does not use a secure comparison.

### Impact

The session id stored in a cookie is the same id that is used when querying the backing session storage engine.  Most storage mechanisms (for example a database) use some sort of indexing in order to speed up the lookup of that id.  By carefully timing requests and session lookup failures, an attacker may be able to perform a timing attack to determine an existing session id and hijack that session.

## Releases

The 1.6.12 and 2.0.8 releases are available at the normal locations.

### Workarounds

There are no known workarounds.

### Patches

To aid users who aren't able to upgrade immediately we have provided patches for
the two supported release series. They are in git-am format and consist of a
single changeset.

* 1-6-session-timing-attack.patch - Patch for 1.6 series
* 2-0-session-timing-attack.patch - Patch for 2.6 series

### Credits

Thanks Will Leinweber for reporting this!