CVE-2026-50733: SHD101WYY Markdown Preview Enhanced

High severity, CVSS 8.8. EPSS: 0.6% chance of exploitation in the next 30 days.

Markdown Preview Enhanced before 0.8.28 parses WaveDrom diagrams by evaluating untrusted markdown content with eval(), allowing arbitrary JavaScript execution. The flaw affects every render path - the live preview (window.eval) and presentation mode plus HTML export (the bundled WaveDrom.ProcessAll()/eva() helpers) - and can also be triggered through a <script type="WaveDrom"> element injected via raw HTML in markdown. When a victim previews or exports a crafted markdown document, an attacker can execute arbitrary code, leading to arbitrary file write. Fixed in 0.8.28 by parsing with JSON5.parse() and sanitizing WaveDrom data scripts to inert strict JSON.

Affected products

• SHD101WYY Markdown Preview Enhanced: before 0.8.28 (fixed in 0.8.28)

Published 2026-06-05. Last modified 2026-06-17.