CVE-2026-28420: vim Heap-based Buffer Overflow

Vulnerability summary

CVE-2026-28420 is a medium (CVSS 4.4) Heap-based Buffer Overflow vulnerability in vim. EPSS estimates a 0.19% chance of exploitation in the next 30 days, higher than 7.9% of scored vulnerabilities.

Timeline

1. 27-02-2026
   PublishedVulnerability first disclosed.
2. 02-03-2026
   Last modifiedVulnerability information updated.

Description

Vim is an open source, command line text editor. Prior to version 9.2.0076, a heap-based buffer overflow WRITE and an out-of-bounds READ exist in Vim's terminal emulator when processing maximum combining characters from Unicode supplementary planes. Version 9.2.0076 fixes the issue.

• 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().
• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.