Out-of-bounds write in Mozilla Firefox and Firefox ESR - CVE-2025-4919,CVE-2025-4921
Published: May 18, 2025 / Updated: May 22, 2025
Vulnerability identifier: #VU109401
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2025-4919,CVE-2025-4921
CWE-ID: CWE-787
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Mozilla
Affected software:
Mozilla Firefox
Firefox ESR
Mozilla Firefox
Firefox ESR
Detailed vulnerability description
The vulnerability allows a remote attacker to compromise vulnerable system.
The vulnerability exists due to a boundary error when manipulating a JavaScript object by confusing array index sizes. A remote attacker can trick the victim into visiting a specially crafted website, trigger an out-of-bounds write and execute arbitrary code on the target system.
How to mitigate CVE-2025-4919,CVE-2025-4921
Install updates from vendor's website.
Sources
- https://bugzilla.mozilla.org/show_bug.cgi?id=1966614
- https://www.mozilla.org/security/advisories/mfsa2025-36/
- https://www.mozilla.org/security/advisories/mfsa2025-37/
- https://www.mozilla.org/en-US/security/advisories/mfsa2025-38/
- https://www.zerodayinitiative.com/advisories/ZDI-25-292/
- https://www.zerodayinitiative.com/advisories/ZDI-25-291/