CVE-2025-1942 — Use of Uninitialized Resource in Mozilla Firefox

CWE-908 — Use of Uninitialized ResourceCWE-824 — Access of Uninitialized Pointer11 documents8 sources
Severity
9.8CRITICALNVD
OSV7.5
EPSS
0.5%
top 35.55%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Mozilla FirefoxMozilla Thunderbird
Timeline
PublishedMar 4
Latest updateFeb 2

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.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitability: 3.9 | Impact: 5.9

Affected Packages4 packages

▶NVDmozilla/firefox< 136.0
▶NVDmozilla/thunderbird< 136.0
▶Ubuntumozilla/firefox< 136.0+build3-0ubuntu0.20.04.1
▶Ubuntumozilla/thunderbird< 1:140.7.1+build1-0ubuntu0.22.04.1

🔴Vulnerability Details

4
OSV
firefox vulnerabilities↗2025-03-06
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OSV
CVE-2025-1942: When String↗2025-03-04
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CVEList
Disclosure of uninitialized memory when .toUpperCase() causes string to get longer↗2025-03-04
▶
GHSA
GHSA-r83v-rmq7-r5m4: When String↗2025-03-04
▶

📋Vendor Advisories

6
Ubuntu
Thunderbird vulnerabilities↗2026-02-02
▶
Ubuntu
Firefox vulnerabilities↗2025-03-06
▶
Red Hat
firefox: Disclosure of uninitialized memory when .toUpperCase() causes string to get longer↗2025-03-04
▶
Debian
CVE-2025-1942: firefox - When String.toUpperCase() caused a string to get longer it was possible for unin...↗2025
▶
Mozilla
Mozilla Foundation Security Advisory 2025-14: CVE-2025-1942↗
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CVE-2025-1942 — Use of Uninitialized Resource | cvebase