CVE-2016-9904: Debian Linux

High severity, CVSS 7.5. EPSS: 2.7% chance of exploitation in the next 30 days.

An attacker could use a JavaScript Map/Set timing attack to determine whether an atom is used by another compartment/zone in specific contexts. This could be used to leak information, such as usernames embedded in JavaScript code, across websites. This vulnerability affects Firefox < 50.1, Firefox ESR < 45.6, and Thunderbird < 45.6.

Affected products

• Debian Debian Linux: version 8.0 only
• Mozilla Firefox: before 45.6.0 (fixed in 45.6.0); before 51.0 (fixed in 51.0)
• Mozilla Thunderbird: before 45.6.0 (fixed in 45.6.0)
• Red Hat Enterprise Linux Desktop: version 5.0 only; version 6.0 only; version 7.0 only
• Red Hat Enterprise Linux Server: version 5.0 only; version 6.0 only; version 7.0 only
• Red Hat Enterprise Linux Workstation: version 5.0 only; version 6.0 only; version 7.0 only

Published 2018-06-11. Last modified 2026-06-17.