Vulnerability Description
An attacker was able to perform an out-of-bounds read or write on a JavaScript `Promise` object. This vulnerability was fixed in Firefox 138.0.4, Firefox ESR 128.10.1, Firefox ESR 115.23.1, Thunderbird 128.10.2, and Thunderbird 138.0.2.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 115.23.1 |
| Mozilla | Thunderbird | < 128.10.2 |
Related Weaknesses (CWE)
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1966612Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2025-36/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-37/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-38/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-40/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-41/Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2025/05/msg00024.html
- https://lists.debian.org/debian-lts-announce/2025/05/msg00046.html
- https://www.vicarius.io/vsociety/posts/cve-2025-4918-detect-firefox-out-of-boundExploitThird Party Advisory
- https://www.vicarius.io/vsociety/posts/cve-2025-4918-mitigate-firefox-out-of-bouExploitThird Party Advisory
FAQ
What is CVE-2025-4918?
CVE-2025-4918 is a vulnerability with a CVSS score of 9.8 (CRITICAL). An attacker was able to perform an out-of-bounds read or write on a JavaScript `Promise` object. This vulnerability was fixed in Firefox 138.0.4, Firefox ESR 128.10.1, Firefox ESR 115.23.1, Thunderbir...
How severe is CVE-2025-4918?
CVE-2025-4918 has been rated CRITICAL with a CVSS base score of 9.8/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2025-4918?
Check the references section above for vendor advisories and patch information. Affected products include: Mozilla Firefox, Mozilla Thunderbird.