Out-of-bounds Read in Mozilla Firefox
CVE-2026-6786
Memory safety bugs present in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited…
Vulnerability class: Buffer Overflow
EPSS: 0.000 (4.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H.
Affected products
- Mozilla Firefox — versions 140.10, 150
- Mozilla Thunderbird — versions 140.10, 150
Weakness classification (CWE)
References
- security@mozilla.org (Broken Link)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-6786?
- CVE-2026-6786 is a high-severity vulnerability in Mozilla Firefox, classified under Out-of-bounds Read. CVSS score: 7.5/10. Published 2026-04-26.
- How severe is CVE-2026-6786?
- High severity. CVSS v3 base score is 7.5 out of 10.