# CVE-2019-16782: ruby-rack: There's a possible information leak / session hijack vulnerability in Rack (RubyGem rack)

CVE-2019-16782 is fixed in ruby-rack on 1 platform, first by ruby-rack 1.6.4-4ubuntu0.2+esm1, released December 18, 2019. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2019-16782
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.0370
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Dec 18, 2019

## Description

There's a possible information leak / session hijack vulnerability in Rack (RubyGem rack). This vulnerability is patched in versions 1.6.12 and 2.0.8. 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | ruby-rack Ubuntu 18.04.6 LTS (bionic) | 1.6.4-4ubuntu0.2+esm1 | [ruby-rack 1.6.4-4ubuntu0.2+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-ruby-rack-1.6.4-4ubuntu0.2-esm1.md) | Dec 18, 2019 |
| Linux | ruby-rack Ubuntu 20.04 LTS (focal) | 2.0.7-2ubuntu0.1+esm1 | [ruby-rack 2.0.7-2ubuntu0.1+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-ruby-rack-2.0.7-2ubuntu0.1-esm1.md) | Dec 18, 2019 |

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