Mozilla Firefox And Thunderbird Type Confusion Vulnerability

HIGH 8.8EXPLOITED (CISA KEV)CVE-2019-17026 · Published 02/03/2020 · updated 17/06/2026

Mozilla Firefox And Thunderbird Type Confusion Vulnerability. Actively exploited: CISA added this vulnerability to its Known Exploited Vulnerabilities catalog on 03/11/2021. Patch affected systems as an emergency.

Package	Affected versions	Patched versions
firefox mozilla	`< 68.4.1< 72.0.1`	`68.4.172.0.1`
thunderbird mozilla	`< 68.4.1`	`68.4.1`

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.

References

packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html · Exploit
bugzilla.mozilla.org/show_bug.cgi · Issue Tracking
security.gentoo.org/glsa/202003-02 · Third Party Advisory
usn.ubuntu.com/4335-1 · Third Party Advisory
mozilla.org/security/advisories/mfsa2020-03 · Vendor Advisory
mozilla.org/security/advisories/mfsa2020-04 · Vendor Advisory
cisa.gov/known-exploited-vulnerabilities-catalog · US Government Resource
CISA KEV · CVE-2019-17026

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