# CVE-2026-28421: Vim has a heap-buffer-overflow and a segmentation fault

> A heap-buffer-overflow in Vim's swap file recovery allows attackers to cause a crash or potentially execute code via crafted swap files.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L`)
- **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:** 27 Feb 2026
- **Updated:** 28 May 2026
- **Also known as:** ALPINE-CVE-2026-28421, AZL-78500, BELL-CVE-2026-28421, DEBIAN-CVE-2026-28421, ECHO-6c94-1f29-8634, GHSA-r2gw-2x48-jj5p, ROOT-OS-DEBIAN-11-CVE-2026-28421, ROOT-OS-DEBIAN-12-CVE-2026-28421

## What is CVE-2026-28421?

CVE-2026-28421 is a medium-severity memory corruption vulnerability in Vim Vim, published on 27 Feb 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. Versions prior to 9.2.0077 have a heap-buffer-overflow and a segmentation fault (SEGV) exist in Vim's swap file recovery logic. Both are caused by unvalidated fields read from crafted pointer blocks within a swap file. Version 9.2.0077 fixes the issue.

Weakness: CWE-20 (Improper Input Validation), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-28421?

It affects 1 product.


Products: Vim Vim.

## How do I fix CVE-2026-28421?

Upgrade to a fixed version.

## Is CVE-2026-28421 being exploited?

There is no known exploitation of CVE-2026-28421 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-2026-28421 and fix it if it is affected.

What it is: CVE-2026-28421 is a medium-severity memory corruption vulnerability in Vim Vim, published on 27 Feb 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-2026-28421 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-2026-28421/ (Markdown: https://insights.sbomify.com/CVE-2026-28421/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-28421
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28421
- OSV: https://osv.dev/vulnerability/CVE-2026-28421

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-28421/
Summaries are generated and may contain mistakes; the official description above is the record.