# CVE-2026-55693: Vim: Out-of-bounds Write in Spell File Word Count

> A crafted spell file can cause an out-of-bounds write in Vim, leading to a crash or potential code execution when spell suggestions are used.

- **Severity:** Medium 5.7 (`CVSS:4.0/AV:L/AC:L/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:** 26 Jun 2026
- **Also known as:** AZL-91107, BELL-CVE-2026-55693, DEBIAN-CVE-2026-55693, ECHO-31d3-7c0e-c6d2, GHSA-wgh4-64f7-q3jq, MINI-83vm-2w88-v66c, ROOT-OS-DEBIAN-11-CVE-2026-55693, ROOT-OS-DEBIAN-12-CVE-2026-55693, UBUNTU-CVE-2026-55693

## What is CVE-2026-55693?

CVE-2026-55693 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 9.2.0653, the tree_count_words() function in src/spellfile.c fills in the word-count fields of a spell-file word trie by walking it iteratively with a depth counter. The counter is bounded only by the trie structure itself; it is never checked against the size of the fixed MAXWLEN-element stack arrays it indexes (arridx[], curi[], wordcount[]). A crafted .spl/.sug file pair, loaded when the user invokes spell suggestion, can drive the descent arbitrarily deep, so the function writes past the end of those arrays. This is a stack out-of-bounds write that corrupts the call frame and crashes the editor. This vulnerability is fixed in 9.2.0653.

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

## Which versions are affected by CVE-2026-55693?

It affects 1 product.


Products: Vim Vim.

## How do I fix CVE-2026-55693?

Upgrade to a fixed version.

## Is CVE-2026-55693 being exploited?

There is no known exploitation of CVE-2026-55693 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-2026-55693 and fix it if it is affected.

What it is: CVE-2026-55693 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-2026-55693 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-2026-55693/ (Markdown: https://insights.sbomify.com/CVE-2026-55693/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55693
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55693
- OSV: https://osv.dev/vulnerability/CVE-2026-55693

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-55693/
Summaries are generated and may contain mistakes; the official description above is the record.