CVE-2025-6436

Memory safety bugs fixed in Firefox 140 and Thunderbird 140

CVSS 8.1 HIGHEPSS 2.9%CWE-119

Vexday Risk Score

21Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 8.1EPSS 2.9%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

24 Jun 2025Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Mozilla · Firefox Mozilla · Thunderbird

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References

https://bugzilla.mozilla.org/buglist.cgi?bug_id=1941377%2C1960948%2C1966187%2C1966505%2C1970764%2C1942930 https://www.mozilla.org/security/advisories/mfsa2025-51/https://www.mozilla.org/security/advisories/mfsa2025-54/