Vim <9.2.0076 Heap OOB Buf Read/Write via Max Unicode Combining
CVE-2026-28420 Published on February 27, 2026
Vim has Heap-based Buffer Overflow and OOB Read in :terminal
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.
Vulnerability Analysis
CVE-2026-28420 is exploitable with local system access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, with no impact on integrity and availability.
Weakness Types
Heap-based Buffer Overflow
A 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().
Out-of-bounds Read
The software reads data past the end, or before the beginning, of the intended buffer. Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.
Products Associated with CVE-2026-28420
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Affected Versions
vim Version < 9.2.0076 is affected by CVE-2026-28420Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.