What’s Vulnerable › Vulnerabilities

CVE-2016-9904

• Severity: high (CVSS 7.5 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2018-06-11 · updated 2026-06-17
• Weakness: CWE-200

Description

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 Linux: 8.0
• Mozilla Firefox: before 45.6.0; before 51.0 — fixed in 45.6.0, 51.0
• Mozilla Thunderbird: before 45.6.0 — fixed in 45.6.0
• RedHat Enterprise Linux Desktop: 5.0, 6.0, 7.0
• RedHat Enterprise Linux Server: 5.0, 6.0, 7.0
• RedHat Enterprise Linux Workstation: 5.0, 6.0, 7.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 45.6.0, 51.0; Mozilla Thunderbird 45.6.0. Check the vendor advisory for mitigations.

References

• http://rhn.redhat.com/errata/RHSA-2016-2946.html
• http://www.securityfocus.com/bid/94885
• http://www.securitytracker.com/id/1037461
• https://bugzilla.mozilla.org/show_bug.cgi?id=1317936
• https://security.gentoo.org/glsa/201701-15
• https://www.debian.org/security/2017/dsa-3757
• https://www.mozilla.org/security/advisories/mfsa2016-94/
• https://www.mozilla.org/security/advisories/mfsa2016-95/
• https://www.mozilla.org/security/advisories/mfsa2016-96/
• http://rhn.redhat.com/errata/RHSA-2016-2946.html
• http://www.securityfocus.com/bid/94885
• http://www.securitytracker.com/id/1037461

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