Mitigation Bypass in DOM Security Component of Firefox
CVE-2026-100829

9.6CRITICAL

Key Information:

Vendor

Mozilla
Status
Firefox
Thunderbird
Vendor
CVE Published:
29 September 2026

What is CVE-2026-100829?

A vulnerability has been identified in the DOM security component of Firefox, which allows for a bypass of established mitigations. This loophole poses significant risks as it could enable adversaries to exploit weaknesses in the browser's security frameworks. Mozilla has issued patches in Firefox ESR 153.4 and Firefox 157 to address this issue. Users are strongly encouraged to update to these versions to maintain a secure browsing environment and protect against potential threats.

Affected Version(s)

Firefox 153.4

Firefox 157

Thunderbird 153.4

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2066321
https://www.mozilla.org/security/advisories/mfsa2026-100/
https://www.mozilla.org/security/advisories/mfsa2026-101/

CVSS V3.1

Score:
9.6
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Rintaro Kawasugi
.