Buffer overflow in Mozilla Firefox
CVE-2026-0878
Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 147, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.
Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.0 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.005 (38.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 38.8% 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: 0.005 · change: +0.000
Affected products
- Mozilla Firefox — versions 140.7, 147
- Mozilla Thunderbird — versions 140.7, 147
Weakness classification (CWE)
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2026-01/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-03/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-04/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-05/ (Vendor Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-0878?
- CVE-2026-0878 is a high-severity vulnerability in Mozilla Firefox, classified under Improper Input Validation. CVSS score: 8.0/10. Published 2026-01-13.
- How severe is CVE-2026-0878?
- High severity. CVSS v3 base score is 8.0 out of 10.