What is CVE-2026-16404?

CVE-2026-16404 is a high-severity vulnerability in Mozilla Firefox, classified under Authentication Bypass by Spoofing. CVSS score: 7.4/10. Published 2026-07-21.

How severe is CVE-2026-16404?

High severity. CVSS v3 base score is 7.4 out of 10.

Vulnerability in Mozilla Firefox

CVE-2026-16404

Spoofing issue in Firefox for Android. This vulnerability was fixed in Firefox 153.

EPSS: 0.002 (5.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N.

Affected products

Mozilla Firefox — versions 153
Mozilla Firefox_mobile

Weakness classification (CWE)

CWE-290 — Authentication Bypass by Spoofing

References

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

Frequently asked questions

What is CVE-2026-16404?: CVE-2026-16404 is a high-severity vulnerability in Mozilla Firefox, classified under Authentication Bypass by Spoofing. CVSS score: 7.4/10. Published 2026-07-21.
How severe is CVE-2026-16404?: High severity. CVSS v3 base score is 7.4 out of 10.