Vulnerability in Mozilla Firefox
CVE-2025-1942
When String.toUpperCase() caused a string to get longer it was possible for uninitialized memory to be incorporated into the result string. This vulnerability was fixed in Firefox 136 and Thunderbird 136.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (39.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 39.1% 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 136
- Mozilla Thunderbird — versions 136
Weakness classification (CWE)
Public proof-of-concept exploits
References
- bugzilla.mozilla.org/show_bug.cgi (Issue Tracking)
- www.mozilla.org/security/advisories/mfsa2025-14/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-17/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2025-1942?
- CVE-2025-1942 is a critical-severity vulnerability in Mozilla Firefox, classified under Use of Uninitialized Resource. CVSS score: 9.8/10. Published 2025-03-04.
- How severe is CVE-2025-1942?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2025-1942 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.