Buffer overflow in Mozilla Firefox
CVE-2026-4729
Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability…
Vulnerability class: Buffer Overflow
EPSS: 0.003 (25.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Mozilla Firefox — versions 149
- Mozilla Thunderbird — versions 149
Weakness classification (CWE)
References
- security@mozilla.org (Broken Link)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-4729?
- CVE-2026-4729 is a critical-severity vulnerability in Mozilla Firefox, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2026-03-24.
- How severe is CVE-2026-4729?
- Critical severity. CVSS v3 base score is 9.8 out of 10.