CVE-2026-25749
Analyzed Analyzed - Analysis Complete
Heap Buffer Overflow in Vim Tag File Resolution (Pre

Publication date: 2026-02-06

Last updated on: 2026-06-09

Assigner: GitHub, Inc.

Description
Vim is an open source, command line text editor. Prior to version 9.1.2132, a heap buffer overflow vulnerability exists in Vim's tag file resolution logic when processing the 'helpfile' option. The vulnerability is located in the get_tagfname() function in src/tag.c. When processing help file tags, Vim copies the user-controlled 'helpfile' option value into a fixed-size heap buffer of MAXPATHL + 1 bytes (typically 4097 bytes) using an unsafe STRCPY() operation without any bounds checking. This issue has been patched in version 9.1.2132.
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Meta Information
Published
2026-02-06
Last Modified
2026-06-09
Generated
2026-06-16
AI Q&A
2026-02-07
EPSS Evaluated
2026-06-15
NVD
CVE-2026-25749
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
vim vim to 9.1.2132 (exc)
neovim neovim to 0.11.6 (inc)
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Exploitability
CWE
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KEV
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CWE ID Description
CWE-122 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().
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Executive Summary

This vulnerability is a heap buffer overflow in the Vim text editor, specifically in the tag file resolution logic when processing the 'helpfile' option.

The issue occurs in the get_tagfname() function in the source code file src/tag.c, where Vim copies the user-controlled 'helpfile' option value into a fixed-size heap buffer without checking if the input fits, using an unsafe STRCPY() operation.

Because the buffer size is fixed (MAXPATHL + 1 bytes, typically 4097 bytes), if the input is larger, it can overflow the buffer, leading to potential memory corruption.

This vulnerability was fixed in Vim version 9.1.2132.

Impact Analysis

The vulnerability can lead to a heap buffer overflow, which may allow an attacker to cause a denial of service or potentially execute arbitrary code with the privileges of the user running Vim.

According to the CVSS v3.1 score, the attack requires local access with low privileges and user interaction, but it can result in high impact on integrity and availability.

Compliance Impact

I don't know

Detection Guidance

I don't know

Mitigation Strategies

To mitigate this vulnerability, you should upgrade Vim to version 9.1.2132 or later, where the heap buffer overflow issue in the get_tagfname() function has been patched.

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