Vulnerability · Published Mar 4, 2025 · Assigned by mozilla
CVE-2025-1942Disclosure of uninitialized memory when .toUpperCase() causes string to get longer
Critical 9.8
In plain English
A critical-severity security flaw in Firefox from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)9.8Critical
Exploit odds (30 days)0.5%top 58.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:22.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2025-1942 |
| Ubuntu:24.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2025-1942 |
| Ubuntu:24.04:LTS | mozjs115 | no fix listed | UBUNTU-CVE-2025-1942 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2025-1942 |
| Ubuntu:22.04:LTS | mozjs91 | no fix listed | UBUNTU-CVE-2025-1942 |
| Ubuntu:22.04:LTS | thunderbird | 1:140.7.1+build1-0ubuntu0.22.04.1 | UBUNTU-CVE-2025-1942 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | see references |
| Mozilla | Thunderbird | see references |
Weakness: CWE-908 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H