What is CVE-2026-6760?

CVE-2026-6760 is a critical-severity vulnerability in Mozilla Firefox, classified under Authentication Bypass Using an Alternate Path or Channel. CVSS score: 9.8/10. Published 2026-04-21.

How severe is CVE-2026-6760?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Vulnerability in Mozilla Firefox

CVE-2026-6760

Mitigation bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.

EPSS: 0.003 (19.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Mozilla Firefox — versions 150
Mozilla Thunderbird — versions 150

Weakness classification (CWE)

CWE-288 — Authentication Bypass Using an Alternate Path or Channel

References

security@mozilla.org (Permissions Required)
security@mozilla.org (Vendor Advisory)
security@mozilla.org (Vendor Advisory)

Frequently asked questions

What is CVE-2026-6760?: CVE-2026-6760 is a critical-severity vulnerability in Mozilla Firefox, classified under Authentication Bypass Using an Alternate Path or Channel. CVSS score: 9.8/10. Published 2026-04-21.
How severe is CVE-2026-6760?: Critical severity. CVSS v3 base score is 9.8 out of 10.