CVE-2025-1942
CRITICALCVSS 9.8/10EPSS 0.45%
Last modified
CVE-2025-1942 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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.. EPSS estimates a 0.45% chance of exploitation in the next 30 days.
Description
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 136.0 |
| Mozilla | Thunderbird | < 136.0 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1947139Issue Tracking
- https://www.mozilla.org/security/advisories/mfsa2025-14/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-17/Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is 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.
How severe is CVE-2025-1942?
CVE-2025-1942 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.45% probability of exploitation in the next 30 days.
How do I fix CVE-2025-1942?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
Are you affected by CVE-2025-1942?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST