What’s Vulnerable › Vulnerabilities

CVE-2019-11707: Mozilla Firefox and Thunderbird Type Confusion Vulnerability

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2022-05-23
• EPSS: 37.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2019-07-23 · updated 2026-06-17
• Weakness: CWE-843

Description

A type confusion vulnerability can occur when manipulating JavaScript objects due to issues in Array.pop. This can allow for an exploitable crash. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 60.7.1, Firefox < 67.0.3, and Thunderbird < 60.7.2.

Affected products

• Mozilla Firefox: before 60.7.1; before 67.0.3 — fixed in 60.7.1, 67.0.3
• Mozilla Thunderbird: before 60.7.2 — fixed in 60.7.2

How to fix

Upgrade to a fixed version: Mozilla Firefox 60.7.1, 67.0.3; Mozilla Thunderbird 60.7.2. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1544386
• https://security.gentoo.org/glsa/201908-12
• https://www.mozilla.org/security/advisories/mfsa2019-18/
• https://www.mozilla.org/security/advisories/mfsa2019-20/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1544386
• https://security.gentoo.org/glsa/201908-12
• https://www.mozilla.org/security/advisories/mfsa2019-18/
• https://www.mozilla.org/security/advisories/mfsa2019-20/
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-11707

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