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TI-2026-37396 Aliases CVE-2026-50733GHSA-j39p-jf99-v5w8

Markdown Preview Enhanced Arbitrary Code Execution via WaveDrom eval()

Priority HIGH 72CWE-95Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Active
Attack complexity
Low
Attack requirements
None
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-95.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00667 52nd percentileScored 2026-11-07
Fix Fixed Markdown Preview Enhanced (shd101wyy): 0.8.28

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
shd101wyyMarkdown Preview Enhancedbefore 0.8.280.8.28Patch availableCNA
  • Markdown Preview Enhanced Vendorshd101wyy Affected before 0.8.28 Fixed in 0.8.28 Patch available CNA

Remediation

  • Fix · CNA Markdown Preview Enhanced (shd101wyy) Fixed in 0.8.28

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    shd101wyy Markdown Preview Enhanced 0.8.28

    3 records Highest priority Priority HIGH 1 HIGH, 2 LOW

    Other records, highest priority first

    • TI-2026-36643 Markdown Preview Enhanced Arbitrary Code Execution via Bitfield interpretJS()Priority LOW 39
    • TI-2026-36642 Markdown Preview Enhanced OS Command Injection in External File and Link OpeningPriority LOW 39
    Show all 3 records →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-50733
  2. 2026-10-03 Alias added: GHSA-j39p-jf99-v5w8
  3. 2026-10-21 EPSS moved to the 50th–90th percentile
  4. 2026-10-25 EPSS moved to the below the 50th percentile
  5. 2026-10-27 EPSS moved to the 50th–90th percentile

References

Other 2

  • TI-2025-40425 An issue in Visual Studio Code Extensions Markdown Preview Enhanced v0.8.18 allows… CVSS 3.1HIGH 8.8
  • TI-2026-74453 Sandbox escape in Markdown Preview Enhanced allows code execution CVSS 4.0HIGH 8.5
  • TI-2026-09857 Markdown Preview Enhanced 0.8.x Code Injection via WaveDrom Rendering CVSS 4.0HIGH 8.4
  • TI-2026-74455 Unvalidated command dispatch in Markdown Preview Enhanced extension CVSS 4.0HIGH 7.3
  • TI-2026-74454 Cross-site scripting in Markdown Preview Enhanced VS Code extension CVSS 4.0MEDIUM 6.9
  • TI-2026-74456 Arbitrary file write in Markdown Preview Enhanced for VS Code CVSS 4.0MEDIUM 5.8
See all 9 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences