# CVE-2026-52859: Vim: Out-of-bounds Read in Terminal Screen Snapshot

> An out-of-bounds read in Vim's terminal snapshot function allows a crash when rendering specific combining characters in a terminal window.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Jun 2026
- **Updated:** 11 Jun 2026
- **Also known as:** ALPINE-CVE-2026-52859, AZL-89772, BELL-CVE-2026-52859, CLSA-2026-1782143534, CLSA-2026-1782143913, CLSA-2026-1782143942, DEBIAN-CVE-2026-52859, ECHO-ebff-11fa-7124, GHSA-47gw-8gc3-mgcm, MINI-r5wx-jrq8-7h69, UBUNTU-CVE-2026-52859

## What is CVE-2026-52859?

CVE-2026-52859 is a medium-severity memory corruption vulnerability in Vim Vim, published on 11 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Vim is an open source, command line text editor. Prior to version 9.2.0565, the update_snapshot() function in src/terminal.c copies the visible terminal screen into the scrollback buffer when a snapshot is taken. For each screen cell it walks the cell's chars[] array with no upper bound, stopping only when it encounters a NUL terminator. When a cell legitimately fills all VTERM_MAX_CHARS_PER_CELL (6) slots — a base character plus five combining marks — the bundled libvterm returns the array without a terminating NUL, so the loop reads past the fixed six-element array and appends the out-of-bounds values to a buffer reserved for only six characters. A program whose output is rendered inside a :terminal window can trigger this with a short byte sequence and no Vim scripting, leading to a crash. This issue has been patched in version 9.2.0565.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-52859?

It affects 1 product.


Products: Vim Vim.

## How do I fix CVE-2026-52859?

Apply the vendor's patch.

## Is CVE-2026-52859 being exploited?

There is no known exploitation of CVE-2026-52859 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-2026-52859 and fix it if it is affected.

What it is: CVE-2026-52859 is a medium-severity memory corruption vulnerability in Vim Vim, published on 11 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-52859 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-2026-52859/ (Markdown: https://insights.sbomify.com/CVE-2026-52859/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-52859
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-52859
- OSV: https://osv.dev/vulnerability/CVE-2026-52859

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-52859/
Summaries are generated and may contain mistakes; the official description above is the record.