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GHSA-hrqr-hxpp-chr3

MediumCVSS 6.3 / 10
Published Dec 18, 2019·Last modified Mar 13, 2026
Affected Components(0)

No affected components available

Description

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!

Risk Scores
Base Score
6.3

The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a high impact on the confidentiality of the information.

Threat Intelligence
5.8

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
3.69%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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