Description
Memory safety bugs present in Firefox 139 and Thunderbird 139. 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 was fixed in Firefox 140 and Thunderbird 140.
Affected products
mozilla: firefox; mozilla: thunderbird
References3
- www.mozilla.org/security/advisories/mfsa2025-51/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2025-54/ Vendor Advisory
- bugzilla.mozilla.org/buglist.cgi?bug_id=1941377%2C1960948%2C196… Permissions Required
Metrics
- CVSS 3.1
-
8.1
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 4% percentile: 91 · as of 7 November 2026
- CWE
- CWE-119
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