Mitigation Bypass in Networking HTTP Component Affects Firefox by Mozilla
CVE-2026-4700

9.8CRITICAL

Key Information:

Vendor

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

What is CVE-2026-4700?

This vulnerability involves a weakness in the Networking: HTTP component of Firefox that allows a bypass of certain mitigation measures. The flaw affects Firefox versions prior to 149 and Firefox ESR versions before 140.9, potentially exposing users to security risks. Users are urged to update their browsers to the latest versions to ensure protection against this issue.

Affected Version(s)

Firefox < 149

Firefox ESR < 140.9

Thunderbird < 149

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2003766
https://www.mozilla.org/security/advisories/mfsa2026-20/
https://www.mozilla.org/security/advisories/mfsa2026-22/

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

pizzahunthack1
.