CVE-2010-5074: Mozilla Firefox

Medium severity, CVSS 4.3. EPSS: 0.6% chance of exploitation in the next 30 days.

The layout engine in Mozilla Firefox before 4.0, Thunderbird before 3.3, and SeaMonkey before 2.1 executes different code for visited and unvisited links during the processing of Cascading Style Sheets (CSS) token sequences, which makes it easier for remote attackers to obtain sensitive information about visited web pages via a timing attack.

Affected products

• Mozilla Firefox: up to and including 3.6.24; version 3.0 only; version 3.0.1 only; version 3.0.2 only; version 3.0.3 only; version 3.0.4 only; …
• Mozilla Seamonkey: up to and including 2.1; version 1.0 only; version 1.0.1 only; version 1.0.2 only; version 1.0.3 only; version 1.0.4 only; …
• Mozilla Thunderbird: up to and including 3.1.16; version 3.0 only; version 3.0.1 only; version 3.0.2 only; version 3.0.3 only; version 3.0.4 only; …

Published 2011-12-07. Last modified 2026-06-16.