Home/CVE/An attacker was able to perform an out-of-bounds read or write on a JavaScript `Promise` object. This vulnerability was
CVE

CVE-2025-4918

An attacker was able to perform an out-of-bounds read or write on a JavaScript `Promise` object. This vulnerability was

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.

CRITICAL · CVSS 9.8 EPSS 0.00994
Act now
  • Public exploit or PoC is available
  • CVSS base score ≥ 7.0
Sigma rules1 YARA rules0
⬡

Weakness Classification

CWE-125Out-of-bounds Read
CWE-787Out-of-bounds Write
▤

Affected Products & Versions

5
mozilla firefox< 115.23.1
mozilla firefox< 138.0.4
mozilla firefox>= 116.0 and < 128.10.1
mozilla thunderbird< 128.10.2
mozilla thunderbird>= 138.0 and < 138.0.2
⚠

Public Exploits & PoCs

2
pocwww.vicarius.io · cve-2025-4918-detect-firefox-out-of-bounds-writewww.vicarius.io
pocwww.vicarius.io · cve-2025-4918-mitigate-firefox-out-of-bounds-writewww.vicarius.io
◈

Sigma Hunt Rules

1
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
producthighSQLite Firefox Profile Data DB Access
▣

Scoring & Timeline

9.8
CRITICAL · CVSS v3.1 · security@mozilla.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD17 May 2025 · 10:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

30
usnUSN-7663-1
suse-csafSUSE-SU-2025:01813-1
rhsaRHSA-2025:8631Important
rhsaRHSA-2025:8598Important
rhsaRHSA-2025:8630Important
🔗

References & Sources

8
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://bugzilla.mozilla.org/show_bug.cgi?id=1966612Permissions 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
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