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

> A stack out-of-bounds write in Vim's spell checker allows attackers to crash the editor by providing an over-length word when a SOFO-based spell language is active.

- **Severity:** Medium 4.0 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 25 Jun 2026
- **Updated:** 25 Jun 2026
- **Also known as:** ALPINE-CVE-2026-57455, AZL-91101, BELL-CVE-2026-57455, DEBIAN-CVE-2026-57455, ECHO-b8e1-3ec5-6440, GHSA-q8mh-6qm3-25g4, MINI-96hr-wrqg-g586, ROOT-OS-DEBIAN-11-CVE-2026-57455, ROOT-OS-DEBIAN-12-CVE-2026-57455, UBUNTU-CVE-2026-57455

## What is CVE-2026-57455?

CVE-2026-57455 is a medium-severity memory corruption vulnerability in Vim Vim, published on 25 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-57455?

It affects 1 product.


Products: Vim Vim.

## How do I fix CVE-2026-57455?

Upgrade to a fixed version.

## Is CVE-2026-57455 being exploited?

There is no known exploitation of CVE-2026-57455 in the wild and no public exploit code.

## Other vulnerabilities in Vim Vim

- [CVE-2020-20703](https://insights.sbomify.com/CVE-2020-20703/): Memory corruption in n/a (critical 9.8)
- [CVE-2017-6349](https://insights.sbomify.com/CVE-2017-6349/): Integer overflow in n/a (critical 9.8)
- [CVE-2017-6350](https://insights.sbomify.com/CVE-2017-6350/): Integer overflow in n/a (critical 9.8)
- [CVE-2017-5953](https://insights.sbomify.com/CVE-2017-5953/): Integer overflow in n/a (critical 9.8)
- [CVE-2008-3075](https://insights.sbomify.com/CVE-2008-3075/): Command injection in n/a (critical 9.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-57455 and fix it if it is affected.

What it is: CVE-2026-57455 is a medium-severity memory corruption vulnerability in Vim Vim, published on 25 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-57455 in the wild and no public exploit code.

Affected product: Vim Vim. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-57455/ (Markdown: https://insights.sbomify.com/CVE-2026-57455/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-57455
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-57455
- OSV: https://osv.dev/vulnerability/CVE-2026-57455

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-57455/
Summaries are generated and may contain mistakes; the official description above is the record.