{"id":"CVE-2025-4919","title":"An attacker was able to perform an out-of-bounds read or write on a JavaScript object by confusing array index sizes","summary":"An attacker was able to perform an out-of-bounds read or write on a JavaScript object by confusing array index sizes. This vulnerability was fixed in Firefox 138.0.4, Firefox ESR 128.10.1, Firefox ESR 115.23.1, Thunderbird 128.10.2, and …","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","cwe":["CWE-125","CWE-787"],"vendor":"mozilla","product":"firefox","affected":["firefox < 115.23.1","firefox < 138.0.4","firefox >= 116.0, < 128.10.1","thunderbird < 128.10.2","thunderbird >= 138.0, < 138.0.2"],"patched":["firefox 128.10.1","thunderbird 138.0.2"],"published":"2025-05-17","updated":"2026-09-30","sourceUpdated":"2026-09-30T18:10:00.190","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-4919","references":[{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1966614","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-36/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-37/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-38/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-40/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-41/","label":"security@mozilla.org"},{"url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00024.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00046.html","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.08627,"epssPercentile":0.94937,"ingestedAt":"2026-09-30T18:17:24.437Z","slug":"CVE-2025-4919","body":"## Overview\n\nAn attacker was able to perform an out-of-bounds read or write on a JavaScript object by confusing array index sizes. 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.\n\n## Affected\n\n- `firefox < 115.23.1`\n- `firefox < 138.0.4`\n- `firefox >= 116.0, < 128.10.1`\n- `thunderbird < 128.10.2`\n- `thunderbird >= 138.0, < 138.0.2`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `firefox 128.10.1`\n- `thunderbird 138.0.2`","depth":"twilight","depthScore":50,"depthScoreParts":{"impact":48.4,"likelihood":1.7,"exploitation":0,"ransomware":0},"changes":[]}