# CVE-2026-25749: Vim heap buffer overflow in helpfile option handling

Source: https://junglewise.ai/threats/cve-2026-25749-vim-heap-buffer-overflow-in-helpfile-option-handling  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-02-06. Updated: 2026-06-09  
License: CC BY 4.0 with a link back

CVE-2026-25749 · Severity: medium · CVSS 6.6 · Published 2026-02-06

Vim is a widely used open-source text editor. A security vulnerability in how Vim handles its help file settings could allow an attacker to crash the application or potentially gain unauthorized control over a user's system. To exploit this, an attacker would need to trick a user into setting a specially crafted long file path as their help file and then triggering the help command.

Technologies: [Vim](https://junglewise.ai/threats/technologies/vim). Vendors: [Vim](https://junglewise.ai/threats/vendors/vim).

## Quick answers

**Is CVE-2026-25749 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-25749 being exploited in the wild.

**How severe is CVE-2026-25749?** Medium severity, with a CVSS score of 6.6, published 6 February 2026.

**Which products and versions are affected?** Neovim Up to and including 0.11.6; Vim Prior to 9.1.2132.

**Is there a fix for CVE-2026-25749?** A patch was published on 2026-02-05: Vim patch 9.1.2132 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-25749 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-25749?** Check whether you run Neovim or Vim at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A heap buffer overflow exists in the get_tagfname() function within src/tag.c. The vulnerability is caused by the use of an unsafe STRCPY() operation that copies the user-controlled 'helpfile' option (p_hf) into a fixed-size heap buffer (buf) of MAXPATHL + 1 bytes without bounds checking. An attacker can trigger this by setting a 'helpfile' string exceeding 4097 bytes and executing the :help command, leading to heap memory corruption. While primarily a Denial of Service risk, the nature of heap overflows allows for potential arbitrary code execution depending on heap layout. The issue is patched in Vim version 9.1.2132 by replacing the unsafe copy with a length-limited strncpy.

## Affected products

- Vim Vim Prior to 9.1.2132
- Neovim Neovim Up to and including 0.11.6

## Timeline

- 2026-02-05: patched: Vim patch 9.1.2132 released
- 2026-02-05: advisory: GitHub Security Advisory GHSA-5w93-4g67-mm43 published
- 2026-02-06: disclosed: CVE-2026-25749 published to NVD

## References

- [https://github.com/vim/vim/commit/0714b15940b245108e6e9d7aa2260dd849a26fa9](https://github.com/vim/vim/commit/0714b15940b245108e6e9d7aa2260dd849a26fa9)
- [https://github.com/vim/vim/releases/tag/v9.1.2132](https://github.com/vim/vim/releases/tag/v9.1.2132)
- [https://github.com/vim/vim/security/advisories/GHSA-5w93-4g67-mm43](https://github.com/vim/vim/security/advisories/GHSA-5w93-4g67-mm43)

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