CVE-2025-1943: mozilla firefox Heap-based Buffer Overflow

Vulnerability summary

CVE-2025-1943 is a high (CVSS 8.2) Heap-based Buffer Overflow vulnerability in mozilla firefox. EPSS estimates a 0.43% chance of exploitation in the next 30 days, higher than 36.2% of scored vulnerabilities.

Timeline

1. 04-03-2025
   PublishedVulnerability first disclosed.
2. 13-04-2026
   Last modifiedVulnerability information updated.

Description

Memory safety bugs present in Firefox 135 and Thunderbird 135. 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 136 and Thunderbird 136.

• CWE-122Heap-based Buffer OverflowA heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().