Out-of-bounds Read in Mozilla Firefox
CVE-2025-4087
A vulnerability was identified in Thunderbird where XPath parsing could trigger undefined behavior due to missing null checks during attribute access. This could lead to out-of-bounds read access and potentially, memory corruption. This vulnerability was fixed in Firefox 138, Firefox ESR 128.10, Thunderbird 138, and Thunderbird 128.10.
Vulnerability class: Buffer Overflow
EPSS: 0.003 (20.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N.
Affected products
- Mozilla Firefox — versions 128.10, 138
- Mozilla Thunderbird — versions 128.10, 138
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security@mozilla.org (Permissions Required)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2025-4087?
- CVE-2025-4087 is a medium-severity vulnerability in Mozilla Firefox, classified under Out-of-bounds Read. CVSS score: 4.8/10. Published 2025-04-29.
- How severe is CVE-2025-4087?
- Medium severity. CVSS v3 base score is 4.8 out of 10.
- Is CVE-2025-4087 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.