# CVE-2026-55892: Vim stack out-of-bounds write in dump_prefixes

Source: https://junglewise.ai/threats/cve-2026-55892-vim-stack-out-of-bounds-write-in-dump-prefixes  
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-2026-55892 · Severity: medium · CVSS 5.5 · Published 2026-06-25

Vim is a widely used command-line text editor. A vulnerability in how it handles spell-check files could allow a specially crafted file to crash the application. To be affected, a user must open a malicious spell file and trigger a word list dump, which could lead to a denial of service or potential instability in the editor.

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

## Quick answers

**Is CVE-2026-55892 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55892 being exploited in the wild.

**How severe is CVE-2026-55892?** Medium severity, with a CVSS score of 5.5, published 25 June 2026.

**Which products and versions are affected?** Vim < 9.2.0662.

**Is there a fix for CVE-2026-55892?** A patch was published on 2026-06-16: Patch v9.2.0662 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-55892 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-55892?** 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 the dump_prefixes() function within src/spell.c. The vulnerability is caused by a lack of bounds checking on a depth counter when walking a spell-file prefix trie. An attacker can provide a crafted .spl file containing self-referential nodes to drive the iterative walker beyond the fixed MAXWLEN-element stack arrays (prefix[], arridx[], and curi[]). This results in a stack corruption that crashes the editor. Exploitation requires the user to load the malicious spell file and execute a command that dumps the word list, such as :spelldump. The issue is fixed in version 9.2.0662.

## Affected products

- Vim Vim < 9.2.0662

## Timeline

- 2026-06-16: patched: Patch v9.2.0662 released
- 2026-06-25: disclosed: Public advisory published

## References

- [https://github.com/vim/vim/commit/8325b193bba5f01e7a7d8241f](https://github.com/vim/vim/commit/8325b193bba5f01e7a7d8241f)
- [https://github.com/vim/vim/releases/tag/v9.2.0662](https://github.com/vim/vim/releases/tag/v9.2.0662)
- [https://github.com/vim/vim/security/advisories/GHSA-qm9w-fmpj-879h](https://github.com/vim/vim/security/advisories/GHSA-qm9w-fmpj-879h)

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