CVE-2025-4918 — Out-of-bounds Read in Mozilla Firefox

CWE-125 — Out-of-bounds ReadCWE-787 — Out-of-bounds Write13 documents9 sources
Severity
9.8CRITICALNVD
EPSS
0.6%
top 30.14%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Mozilla ThunderbirdMozilla Firefox
Timeline
PublishedMay 17
Latest updateJul 22

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 vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitability: 3.9 | Impact: 5.9

Affected Packages3 packages

▶NVDmozilla/firefox116.0 — 128.10.1+2
▶NVDmozilla/thunderbird138.0 — 138.0.2+1
▶Debianmozilla/thunderbird< 1:128.11.0esr-1~deb11u1+3

🔴Vulnerability Details

3
GHSA
GHSA-fhgm-mxgh-gfpj: An attacker was able to perform an out-of-bounds read or write on a JavaScript `Promise` object↗2025-05-18
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OSV
CVE-2025-4918: An attacker was able to perform an out-of-bounds read or write on a JavaScript `Promise` object↗2025-05-17
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CVEList
Out-of-bounds access when resolving Promise objects↗2025-05-17
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📋Vendor Advisories

8
Ubuntu
Thunderbird vulnerabilities↗2025-07-22
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Red Hat
firefox: thunderbird: Out-of-bounds access when resolving Promise objects↗2025-05-17
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Debian
CVE-2025-4918: firefox - An attacker was able to perform an out-of-bounds read or write on a JavaScript `...↗2025
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Mozilla
Mozilla Foundation Security Advisory 2025-36: CVE-2025-4918↗
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Mozilla
Mozilla Foundation Security Advisory 2025-37: CVE-2025-4918↗
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🕵️Threat Intelligence

1
Bleepingcomputer
Mozilla fixes Firefox zero-days exploited at hacking contest↗2025-05-19
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CVE-2025-4918 — Out-of-bounds Read in Mozilla Firefox | cvebase