Mitigation Bypass Vulnerability in Firefox by Mozilla
CVE-2026-2784

9.8CRITICAL

Key Information:

Vendor

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

What is CVE-2026-2784?

A mitigation bypass vulnerability exists in the security component of the Document Object Model (DOM) in Firefox, which potentially allows attackers to circumvent intended security features. This affects specific versions of Firefox and Firefox Extended Support Release (ESR), making them susceptible to unauthorized access and malicious activities. Users of versions prior to 148 and ESR versions prior to 140.8 are particularly at risk, emphasizing the need for immediate updates and robust security practices.

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Affected Version(s)

Firefox < 148

Firefox ESR < 140.8

Thunderbird < 148

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2012984
https://www.mozilla.org/security/advisories/mfsa2026-13/
https://www.mozilla.org/security/advisories/mfsa2026-15/

CVSS V3.1

Score:
9.8
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

D. Santos
JSON
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