Buffer overflow in Mozilla Firefox
CVE-2025-5268
Memory safety bugs present in Firefox 138, Thunderbird 138, Firefox ESR 128.10, and Thunderbird 128.10. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 139, Firefox ESR 128.11, Thunderbird 139, and Thunderbird 128.11.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (39.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 39.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Mozilla Firefox — versions 128.11, 139
- Mozilla Thunderbird — versions 128.11, 139
Weakness classification (CWE)
Public proof-of-concept exploits
References
- bugzilla.mozilla.org/buglist.cgi (Broken Link)
- www.mozilla.org/security/advisories/mfsa2025-42/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-44/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-45/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-46/ (Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2025-5268?
- CVE-2025-5268 is a high-severity vulnerability in Mozilla Firefox, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 8.1/10. Published 2025-05-27.
- How severe is CVE-2025-5268?
- High severity. CVSS v3 base score is 8.1 out of 10.
- Is CVE-2025-5268 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.