CVE-2025-68142
📋 TL;DR
PyMdown Extensions versions before 10.16.1 contain a ReDoS vulnerability in the figure caption extension that allows attackers to cause denial of service by submitting specially crafted malicious content. Systems that process untrusted user input without proper safeguards are affected. The vulnerability can cause long processing hangs when parsing malicious payloads.
💻 Affected Systems
- PyMdown Extensions
📦 What is this software?
Pymdown Extensions by Facelessuser
⚠️ Risk & Real-World Impact
Worst Case
Complete denial of service causing system unavailability due to resource exhaustion from processing malicious payloads
Likely Case
Degraded performance and service disruption when processing malicious user content
If Mitigated
Minimal impact with proper timeouts and input validation in place
🎯 Exploit Status
Exploitation requires submitting malicious content to systems processing markdown with the vulnerable extension
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.16.1
Vendor Advisory: https://github.com/facelessuser/pymdown-extensions/security/advisories/GHSA-r6h4-mm7h-8pmq
Restart Required: No
Instructions:
1. Update PyMdown Extensions using pip: pip install --upgrade pymdown-extensions==10.16.1
2. Verify the update completed successfully
3. No restart required for Python applications
🔧 Temporary Workarounds
Disable vulnerable extension
allDisable the pymdownx.blocks.caption extension until patching is possible
Modify your markdown configuration to remove or disable 'pymdownx.blocks.caption'
🧯 If You Can't Patch
- Implement strict input validation and size limits on user-submitted content
- Add processing timeouts and resource limits to markdown processing functions
🔍 How to Verify
Check if Vulnerable:
Check PyMdown Extensions version: pip show pymdown-extensions | grep VersionCheck Version:
pip show pymdown-extensions | grep VersionVerify Fix Applied:
Verify version is 10.16.1 or higher: pip show pymdown-extensions | grep Version📡 Detection & Monitoring
Log Indicators:
- Unusually long processing times for markdown content
- High CPU usage spikes during content processing
- Timeout errors in markdown processing functions
Network Indicators:
- Repeated submissions of large or complex markdown content
- Patterns of content designed to trigger regex processing
SIEM Query:
source="application.logs" AND ("markdown processing" OR "pymdown") AND (duration>10s OR "timeout" OR "hang")