Privilege escalation in Mozilla Firefox
CVE-2026-92015
Privilege escalation in the WebExtensions component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.
Vulnerability class: Privilege Escalation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.003 (17.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 17.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: -0.000
Affected products
Weakness classification (CWE)
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2026-90/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-91/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-92/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-93/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-95/ (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-2026-92015?
- CVE-2026-92015 is a high-severity vulnerability in Mozilla Firefox, classified under Improper Privilege Management. CVSS score: 8.8/10. Published 2026-09-15.
- How severe is CVE-2026-92015?
- High severity. CVSS v3 base score is 8.8 out of 10.