Vulnerability-Lookup

GHSA-J39P-JF99-V5W8

Vulnerability from github – Published: 2026-06-05 18:31 – Updated: 2026-06-05 18:31

Details

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 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.

Severity

8.8 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

8.6 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Show details on source website

JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-50733"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-95"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-06-05T18:17:34Z",
    "severity": "HIGH"
  },
  "details": "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 \u003cscript type=\"WaveDrom\"\u003e 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.",
  "id": "GHSA-j39p-jf99-v5w8",
  "modified": "2026-06-05T18:31:41Z",
  "published": "2026-06-05T18:31:41Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-50733"
    },
    {
      "type": "WEB",
      "url": "https://github.com/shd101wyy/vscode-markdown-preview-enhanced/issues/2315"
    },
    {
      "type": "WEB",
      "url": "https://github.com/shd101wyy/vscode-markdown-preview-enhanced/releases/tag/0.8.28"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/markdown-preview-enhanced-arbitrary-code-execution-via-wavedrom-eval"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-50733 (GCVE-0-2026-50733)

Vulnerability from cvelistv5 – Published: 2026-06-05 17:49 – Updated: 2026-06-05 19:03

Title

Markdown Preview Enhanced Arbitrary Code Execution via WaveDrom eval()

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.

Severity

8.6 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

8.8 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator (v2.0.3)

CWE

CWE-95 - Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')

Assigner

VulnCheck

References

3 references

URL	Tags
https://github.com/shd101wyy/vscode-markdown-prev…	release-notes
https://github.com/shd101wyy/vscode-markdown-prev…	issue-tracking
https://www.vulncheck.com/advisories/markdown-pre…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
shd101wyy	Markdown Preview Enhanced	Affected: 0 , < 0.8.28 (semver)

Date Public

2026-06-05 00:00

Credits

Neo by ProjectDiscovery

Show details on NVD website

JSON

To clipboard

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  "containers": {
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                "id": "CVE-2026-50733",
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                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-05T19:03:16.138729Z",
                "version": "2.0.3"
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        "providerMetadata": {
          "dateUpdated": "2026-06-05T19:03:27.311Z",
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    ],
    "cna": {
      "affected": [
        {
          "product": "Markdown Preview Enhanced",
          "vendor": "shd101wyy",
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              "status": "affected",
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-J39P-JF99-V5W8

CVE-2026-50733 (GCVE-0-2026-50733)

Tags

Sightings

Nomenclature