JavaScript Engine Vulnerability in Firefox Products by Mozilla
CVE-2026-4716

9.1CRITICAL

Key Information:

Vendor

Mozilla
Status
Firefox
Firefox Esr
Thunderbird
Vendor
CVE Published:
24 March 2026

What is CVE-2026-4716?

This vulnerability is characterized by incorrect boundary conditions and uninitialized memory within the JavaScript Engine of Firefox products. Users of Firefox versions prior to 149 and Firefox Extended Support Release versions prior to 140.9 may face potential security risks due to this issue. It is crucial for users to update their browsers to maintain security integrity and mitigate exploitation risks.

Affected Version(s)

Firefox < 149

Firefox ESR < 140.9

Thunderbird < 149

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2018592
https://www.mozilla.org/security/advisories/mfsa2026-20/
https://www.mozilla.org/security/advisories/mfsa2026-22/

CVSS V3.1

Score:
9.1
Severity:
CRITICAL
Confidentiality:
High
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Pwn2addr
.