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Vulnerability · Published Oct 14, 2026 · Assigned by GitHub_M

CVE-2026-54702Markdown Preview Enhanced: Blind Command Dispatch via Unvalidated Webview Message Handler

High 7.3

In plain English

A high-severity security flaw in vscode-markdown-preview-enhanced from shd101wyy. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities).

Severity (CVSS 4.0)7.3High
Exploit odds (30 days)0.3%top 75.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

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.

Affected products (as reported)

VendorProductVersions
shd101wyy vscode-markdown-preview-enhanced < 0.8.30

Weakness: CWE-749 · Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

References