Mitigation Bypass in Mozilla Firefox Service Workers
CVE-2026-16407

9.8CRITICAL

Key Information:

Vendor

Mozilla
Status
Firefox
Thunderbird
Vendor
CVE Published:
21 July 2026

What is CVE-2026-16407?

A mitigation bypass vulnerability was identified in the Service Workers component of Mozilla Firefox. This flaw allows for unintended behaviors that could potentially bypass security mechanisms. Mozilla addressed this issue in Firefox version 153, enhancing the overall security posture of the web browser. Users are advised to update to ensure protection against potential exploits that may leverage this vulnerability.

Affected Version(s)

Firefox 153

Thunderbird 153

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2044063
https://www.mozilla.org/security/advisories/mfsa2026-68/
https://www.mozilla.org/security/advisories/mfsa2026-71/

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

bug2own
.