Vulnerability in Mozilla Firefox
CVE-2026-84131
Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
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 (25.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 25.3% 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/mfsa2026-82/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-83/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-84/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-85/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-86/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-87/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-88/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-84131?
- CVE-2026-84131 is a high-severity vulnerability in Mozilla Firefox, classified under Release of Invalid Pointer or Reference. CVSS score: 8.8/10. Published 2026-09-01.
- How severe is CVE-2026-84131?
- High severity. CVSS v3 base score is 8.8 out of 10.