# CVE-2026-55693: Vim stack out-of-bounds write in tree_count_words

Source: https://junglewise.ai/threats/cve-2026-55693-vim-stack-out-of-bounds-write-in-tree-count-words  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-25. Updated: 2026-06-25  
License: CC BY 4.0 with a link back

CVE-2026-55693 · Severity: info · CVSS 5.7 · Published 2026-06-25

Vim is a widely used open-source text editor. A vulnerability in how it handles spell-check files allows a specially crafted file to cause the application to crash or potentially execute unauthorized code. To be affected, a user must open a malicious spell-check file and attempt to use the spell-suggestion feature.

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

## Quick answers

**Is CVE-2026-55693 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55693 being exploited in the wild.

**How severe is CVE-2026-55693?** Informational severity, with a CVSS score of 5.7, published 25 June 2026.

**Which products and versions are affected?** Vim < 9.2.0653.

**Is there a fix for CVE-2026-55693?** A patch was published on 2026-06-15: Vim patch 9.2.0653 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-55693 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-55693?** Check whether you run 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 stack-based out-of-bounds write exists in Vim's tree_count_words() function within src/spellfile.c. The vulnerability is caused by a lack of bounds checking on a depth counter used to index fixed-size stack arrays (arridx, curi, and wordcount) during the iterative traversal of a spell-file word trie. An attacker can provide a crafted .spl or .sug file containing cyclic geometries or deep forward-shared chains to exceed the MAXWLEN (254) limit. Exploitation requires the user to have spell-checking enabled and to trigger a spell suggestion (e.g., via 'z='). This results in stack corruption, leading to a crash or potential arbitrary code execution. The issue is resolved in version 9.2.0653 by enforcing depth limits during traversal.

## Affected products

- Vim Vim < 9.2.0653

## Timeline

- 2026-06-15: patched: Vim patch 9.2.0653 released
- 2026-06-15: advisory: GitHub Security Advisory GHSA-wgh4-64f7-q3jq published
- 2026-06-25: disclosed: CVE-2026-55693 published to NVD

## References

- [https://github.com/vim/vim/commit/a80874d9b84a01040e3d1aef2d4a59e1934dafb7](https://github.com/vim/vim/commit/a80874d9b84a01040e3d1aef2d4a59e1934dafb7)
- [https://github.com/vim/vim/releases/tag/v9.2.0653](https://github.com/vim/vim/releases/tag/v9.2.0653)
- [https://github.com/vim/vim/security/advisories/GHSA-wgh4-64f7-q3jq](https://github.com/vim/vim/security/advisories/GHSA-wgh4-64f7-q3jq)

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