Buffer overflow in Mozilla Firefox
CVE-2026-74946
Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
Vulnerability class: Buffer Overflow
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: 0.005 (39.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 39.9% 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: 0.005 · change: +0.002
Affected products
Weakness classification (CWE)
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2026-74/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-75/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-76/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-77/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-78/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-79/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-80/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-74946?
- CVE-2026-74946 is a high-severity vulnerability in Mozilla Firefox, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 8.8/10. Published 2026-08-18.
- How severe is CVE-2026-74946?
- High severity. CVSS v3 base score is 8.8 out of 10.