An attacker was able to perform an out-of-bounds read or write on a JavaScript `Promise` object. This vulnerability affects Firefox < 138.0.4, Firefox ESR < 128.10.1, Firefox ESR < 115.23.1, Thunderbird < 128.10.2, and Thunderbird < 138.0.2.
The product reads data past the end, or before the beginning, of the intended buffer.
| Link | Tags |
|---|---|
| https://bugzilla.mozilla.org/show_bug.cgi?id=1966612 | permissions 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://www.vicarius.io/vsociety/posts/cve-2025-4918-detect-firefox-out-of-bounds-write | third party advisory exploit |
| https://www.vicarius.io/vsociety/posts/cve-2025-4918-mitigate-firefox-out-of-bounds-write | third party advisory exploit |