CVE-2026-6771
CRITICALCVSS 9.8/10EPSS 0.31%
Last modified
CVE-2026-6771 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.. EPSS estimates a 0.31% chance of exploitation in the next 30 days.
Description
Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 150.0 |
| Mozilla | Firefox | >= 140.0, < 140.10.0 |
| Mozilla | Thunderbird | >= 140.0, < 140.10.0 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2025067Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-30/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-32/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-33/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-34/Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-6771?
Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
How severe is CVE-2026-6771?
CVE-2026-6771 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.31% probability of exploitation in the next 30 days.
How do I fix CVE-2026-6771?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
Are you affected by CVE-2026-6771?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST