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CRITICAL

CVE-2025-4918

Out-of-bounds access when resolving Promise objects

CVSS v3

9.8

CRITICAL

EPSS Score

9.4 %

exploit probability, as of 2026-09-25

CISA KEV

No

known exploited

Exploitation

none

SSVC status

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.

Technical details

Published
2025-05-17
Last Modified
2026-04-13

Frequently asked questions

What is CVE-2025-4918?

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.

Is CVE-2025-4918 actively exploited?

Active exploitation of CVE-2025-4918 has not been confirmed. Its EPSS score was 9.4% on 2026-09-25, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2025-4918?

CVE-2025-4918 has a CVSS v3 base score of 9.8 (CRITICAL severity).

Is CVE-2025-4918 affecting your environment?

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