What is CVE-2026-92038?

CVE-2026-92038 is a critical-severity vulnerability in Mozilla Firefox, classified under Protection Mechanism Failure. CVSS score: 9.1/10. Published 2026-09-15.

How severe is CVE-2026-92038?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Vulnerability in Mozilla Firefox

CVE-2026-92038

Mitigation bypass in the Remote Settings Client component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.

Published 2026-09-15 · last modified 2026-10-05.

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.

EPSS exploit prediction

EPSS: 0.003 (24.4th percentile), scored 2026-10-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 24th percentile — 24.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.003 · change: -0.000

Affected products

Weakness classification (CWE)

CWE-693 — Protection Mechanism Failure

References

bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
www.mozilla.org/security/advisories/mfsa2026-90/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2026-93/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2026-94/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2026-96/ (Vendor Advisory)

Frequently asked questions

What is CVE-2026-92038?: CVE-2026-92038 is a critical-severity vulnerability in Mozilla Firefox, classified under Protection Mechanism Failure. CVSS score: 9.1/10. Published 2026-09-15.
How severe is CVE-2026-92038?: Critical severity. CVSS v3 base score is 9.1 out of 10.