Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 140.0 |
| Mozilla | Thunderbird | < 140.0 |
Related Weaknesses (CWE)
References
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=1941377%2C1960948%2C1966187%2C19Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2025-51/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-54/Vendor Advisory
FAQ
What is CVE-2025-6436?
CVE-2025-6436 is a vulnerability with a CVSS score of 8.1 (HIGH). 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...
How severe is CVE-2025-6436?
CVE-2025-6436 has been rated HIGH with a CVSS base score of 8.1/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-6436?
Check the references section above for vendor advisories and patch information. Affected products include: Mozilla Firefox, Mozilla Thunderbird.