# CVE-2026-28420: Vim has Heap-based Buffer Overflow and OOB Read in :terminal

> Heap-based buffer overflow and out-of-bounds read in Vim's terminal emulator allow attackers to execute code or crash the application.

- **Severity:** Medium 4.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/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:** 2 Mar 2026
- **Also known as:** ALPINE-CVE-2026-28420, AZL-78503, BELL-CVE-2026-28420, DEBIAN-CVE-2026-28420, ECHO-e482-e357-798e, GHSA-rvj2-jrf9-2phg

## What is CVE-2026-28420?

CVE-2026-28420 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. Prior to version 9.2.0076, a heap-based buffer overflow WRITE and an out-of-bounds READ exist in Vim's terminal emulator when processing maximum combining characters from Unicode supplementary planes. Version 9.2.0076 fixes the issue.

Weakness: CWE-125 (Out-of-bounds Read), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-28420?

It affects 1 product.


Products: Vim Vim.

## How do I fix CVE-2026-28420?

Upgrade to a fixed version.

## Is CVE-2026-28420 being exploited?

There is no known exploitation of CVE-2026-28420 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-2026-28420 and fix it if it is affected.

What it is: CVE-2026-28420 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-2026-28420 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-2026-28420/ (Markdown: https://insights.sbomify.com/CVE-2026-28420/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-28420
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28420
- OSV: https://osv.dev/vulnerability/CVE-2026-28420

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-28420/
Summaries are generated and may contain mistakes; the official description above is the record.