CVE-2026-54702 Markdown Preview Enhanced: Blind Command Dispatch via Unvalidated Webview Message Handler
Attackers with webview script execution can invoke privileged extension commands to execute code or modify files due to missing input validation in the message handler.
- 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
- None listed
What is CVE-2026-54702?
CVE-2026-54702 is a high-severity code injection vulnerability in shd101wyy vscode-markdown-preview-enhanced, published on 14 Oct 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 is a Markdown preview extension for Visual Studio Code. Prior to 0.8.30, the webview message handler in src/preview-provider.ts accepts an attacker-controlled command value and attacker-controlled args, constructs a command in the _crossnote namespace, and invokes vscode.commands.executeCommand without an allowlist or type validation. JavaScript already executing in the preview webview can use this bridge to invoke privileged extension commands, including file modification, code-chunk execution, export-tool execution, and arbitrary URL opening, with attacker-selected arguments. Exploitation requires a separate webview JavaScript execution path, such as the independently tracked .crossnote/head.html injection, but no further authorization check protects the extension-host command boundary. This issue is fixed in version 0.8.30.
Weakness: CWE-749
Which versions are affected by CVE-2026-54702?
How do I fix CVE-2026-54702?
No fix has been published for CVE-2026-54702 yet. Limit exposure of the affected software until one is available.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-54702 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54702 exists.
Sources
Also known as GHSA-83c6-hcjv-pvmg.