What’s Vulnerable › Vulnerabilities

CVE-2019-17026: Mozilla Firefox And Thunderbird Type Confusion Vulnerability

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2021-11-03
• EPSS: 46.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2020-03-02 · updated 2026-06-17
• Weakness: CWE-843

Description

Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 68.4.1, Thunderbird < 68.4.1, and Firefox < 72.0.1.

Affected products

• Canonical Ubuntu Linux: 16.04
• Mozilla Firefox: before 68.4.1; before 72.0.1 — fixed in 68.4.1, 72.0.1
• Mozilla Thunderbird: before 68.4.1 — fixed in 68.4.1

How to fix

Upgrade to a fixed version: Mozilla Firefox 68.4.1, 72.0.1; Mozilla Thunderbird 68.4.1. Check the vendor advisory for mitigations.

References

• http://packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html
• https://bugzilla.mozilla.org/show_bug.cgi?id=1607443
• https://security.gentoo.org/glsa/202003-02
• https://usn.ubuntu.com/4335-1/
• https://www.mozilla.org/security/advisories/mfsa2020-03/
• https://www.mozilla.org/security/advisories/mfsa2020-04/
• http://packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html
• https://bugzilla.mozilla.org/show_bug.cgi?id=1607443
• https://security.gentoo.org/glsa/202003-02
• https://usn.ubuntu.com/4335-1/
• https://www.mozilla.org/security/advisories/mfsa2020-03/
• https://www.mozilla.org/security/advisories/mfsa2020-04/

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