CVE-2025-4918
9.8
CRITICAL · CVSS 3.1 · EPSS 9.4% (pctl 95)
In your normal cycle
Critical by CVSS (9.8), but no sign of active exploitation.
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.
Scoring
| CVSS | 9.8 (CRITICAL, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| EPSS | 9.38% — more likely to be exploited than 95% of all CVEs |
| Weakness | CWE-125 |
| On CISA KEV | no |
| Public exploit | none known |
| Published | 2025-05-17 |
| Last modified | 2026-09-30 |
Affected (2)
| Vendor | Product |
|---|---|
| mozilla | firefox |
| mozilla | thunderbird |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1966612
- https://www.mozilla.org/security/advisories/mfsa2025-36/
- https://www.mozilla.org/security/advisories/mfsa2025-37/
- https://www.mozilla.org/security/advisories/mfsa2025-38/
- https://www.mozilla.org/security/advisories/mfsa2025-40/
- https://www.mozilla.org/security/advisories/mfsa2025-41/
- 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-bounds-write
- https://www.vicarius.io/vsociety/posts/cve-2025-4918-mitigate-firefox-out-of-bounds-write
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