CVE-2021-47838
📋 TL;DR
Markright 1.0 contains a persistent cross-site scripting (XSS) vulnerability where attackers can embed malicious JavaScript in markdown files. When users open these specially crafted files, arbitrary JavaScript executes in their browser context, potentially leading to session hijacking, credential theft, or remote code execution. This affects all users of Markright 1.0 who open untrusted markdown files.
💻 Affected Systems
- Markright
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise via remote code execution if JavaScript payload exploits browser vulnerabilities, leading to malware installation, data exfiltration, or complete system control.
Likely Case
Session hijacking, credential theft, or unauthorized actions within the user's browser context (like accessing sensitive data or performing actions as the user).
If Mitigated
Limited impact if proper input validation and output encoding are implemented, restricting payload execution to isolated browser sandbox.
🎯 Exploit Status
Exploit requires user interaction (opening malicious markdown file). Public proof-of-concept available on Exploit-DB (ID 49834).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: https://github.com/dvcrn/markright
Restart Required: No
Instructions:
No official patch exists. Consider alternative markdown editors or implement workarounds.
🔧 Temporary Workarounds
Disable JavaScript in Markright
allConfigure Markright to disable JavaScript execution when rendering markdown files.
Check Markright documentation for JavaScript disabling options
Use Content Security Policy (CSP)
allImplement CSP headers to restrict script execution from untrusted sources.
Add 'Content-Security-Policy: script-src 'self'' to HTTP headers
🧯 If You Can't Patch
- Only open markdown files from trusted sources
- Use alternative markdown editors with proper XSS protections
🔍 How to Verify
Check if Vulnerable:
Test by creating a markdown file with XSS payload like '<script>alert("XSS")</script>' and opening in Markright. If alert executes, system is vulnerable.Check Version:
Check Markright 'About' menu or documentation for version information.Verify Fix Applied:
Retest with same XSS payload after implementing workarounds. Alert should not execute.📡 Detection & Monitoring
Log Indicators:
- Unusual file access patterns
- Markright process executing unexpected scripts
Network Indicators:
- Outbound connections from Markright to unknown domains
- Unexpected data exfiltration
SIEM Query:
Process:Markright AND (CommandLine:*script* OR NetworkConnection:External)