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HighPublic exploit

Arbitrary JavaScript Execution in Markdown Preview Enhanced WaveDrom Rendering

IdentifiersCVE-2026-50733CWE-95· Improper Neutralization of…

CVE-2026-50733 affects Markdown Preview Enhanced before 0.8.28. The vulnerability is caused by unsafe evaluation of untrusted markdown-supplied WaveDrom diagram content using eval(). According to the provided content, all rendering paths are affected: live preview via window.eval, presentation mode, and HTML export through bundled WaveDrom.ProcessAll()/eva() helpers. The issue can also be triggered by injecting a <script type="WaveDrom"> element through raw HTML embedded in markdown. When a victim previews or exports a crafted markdown document, attacker-controlled JavaScript is executed in the application context. The vendor fixed the issue in 0.8.28 by replacing eval()-based parsing with JSON5.parse() and sanitizing WaveDrom data scripts into inert strict JSON.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows arbitrary JavaScript execution in the context of Markdown Preview Enhanced when a victim previews or exports a malicious markdown document. Based on the provided content, this can lead to arbitrary file write and high impact to confidentiality, integrity, and availability.

Mitigation

If you can’t patch tonight, do this now.

Do not preview or export untrusted markdown documents until the fixed version is deployed. Where possible, disable or restrict WaveDrom rendering and raw HTML handling in markdown content to reduce exposure. Treat markdown files from untrusted sources as active content because exploitation is triggered during preview or export.

Remediation

Patch, then assume compromise.

Upgrade Markdown Preview Enhanced to version 0.8.28 or later. The fix replaces eval()-based WaveDrom parsing with JSON5.parse() and sanitizes WaveDrom data scripts so they are treated as inert strict JSON rather than executable code.
PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Markdown Preview Enhanced ProjectMarkdown Preview Enhancedapplication

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Threat actor evidence

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Associated malware

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Detection signatures

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Vendor-by-vendor mapping

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Social activity5

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