# CVE-2026-11422: Markdown Preview Enhanced 0.8.x Code Injection via WaveDrom Rendering

> Attackers can execute arbitrary JavaScript and write files by embedding malicious content in WaveDrom blocks within Markdown documents processed by the extension.

- **Severity:** High 8.4 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **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:** No
- **Published:** 5 Jun 2026
- **Updated:** 14 Jul 2026
- **Also known as:** GHSA-m48c-hxqg-4j76

## What is CVE-2026-11422?

CVE-2026-11422 is a high-severity code injection vulnerability in shd101wyy Markdown Preview Enhanced, published on 5 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

Markdown Preview Enhanced 0.8.x with crossnote engine 0.9.28 contains a code injection vulnerability in the WaveDrom rendering pipeline that allows attackers to execute arbitrary JavaScript by embedding malicious content in a wavedrom fenced code block within a crafted Markdown document. Attackers can exploit the unsanitized passing of wavedrom block content to window.eval() in the VS Code webview context to abuse the extension's message passing and invoke arbitrary file writes on the local filesystem.

Weakness: CWE-95 (Improper Neutralization of Directives in Dynamically Evaluated Code)

## Which versions are affected by CVE-2026-11422?


## How do I fix CVE-2026-11422?

No fix has been published for CVE-2026-11422 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-11422 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-11422 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-11422 and fix it if it is affected.

What it is: CVE-2026-11422 is a high-severity code injection vulnerability in shd101wyy Markdown Preview Enhanced, published on 5 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-11422 exists.

Affected product: shd101wyy Markdown Preview Enhanced. 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-2026-11422/ (Markdown: https://insights.sbomify.com/CVE-2026-11422/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-11422
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-11422
- OSV: https://osv.dev/vulnerability/CVE-2026-11422

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-11422/
Summaries are generated and may contain mistakes; the official description above is the record.