Vulnerability in Mozilla Firefox
CVE-2026-16381
Same-origin policy bypass in the Networking: DNS component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.
EPSS: 0.002 (6.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
Affected products
- Mozilla Firefox — versions 140.13, 153
- Mozilla Thunderbird — versions 140.13, 153
Weakness classification (CWE)
References
- security@mozilla.org (Permissions Required)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-16381?
- CVE-2026-16381 is a critical-severity vulnerability in Mozilla Firefox, classified under Origin Validation Error. CVSS score: 9.1/10. Published 2026-07-21.
- How severe is CVE-2026-16381?
- Critical severity. CVSS v3 base score is 9.1 out of 10.