CVE-2025-4918

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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTNIST
9.8 CRITICAL
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
mozillaCNA
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CISA-ADPADP
9.8 CRITICAL
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVEADP
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Base Score
CVSS 3.x
EPSS Score
Percentile: 15%
VendorProductVersion
mozillafirefox
𝑥
< 115.23.1
mozillafirefox
𝑥
< 138.0.4
mozillafirefox
116.0 ≤
𝑥
< 128.10.1
mozillathunderbird
𝑥
< 128.10.2
mozillathunderbird
138.0 ≤
𝑥
< 138.0.2
𝑥
= Vulnerable software versions
Common Weakness Enumeration
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://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