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Vulnerability record · CVE-2025-4918 · published 17 May 2025

CVE-2025-4918: Mozilla firefox out-of-bounds read vulnerability

Mozilla · Firefox

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.

9.8 CVSS 3.1 Critical EPSS 9.4% · top 4.8% CWE-125 · Out-of-bounds readCWE-787 · Out-of-bounds write
9.8CVSS 3.1 base score
9.4%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
10References, 2 tagged exploit
17 Jun 2026Last modified by NVD

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

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
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://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 ExploitThird Party Advisory
https://www.vicarius.io/vsociety/posts/cve-2025-4918-mitigate-firefox-out-of-bounds-write ExploitThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2025-4918), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.