CVE-2025-3636
📋 TL;DR
This vulnerability in Moodle allows unauthorized users to access RSS feeds due to insufficient permission checks. Any Moodle instance with RSS feeds enabled is affected, potentially exposing internal information to unauthenticated users.
💻 Affected Systems
- Moodle
📦 What is this software?
Moodle by Moodle
Moodle by Moodle
Moodle by Moodle
Moodle by Moodle
⚠️ Risk & Real-World Impact
Worst Case
Unauthenticated attackers access sensitive RSS feeds containing internal course information, announcements, or user data that should be restricted.
Likely Case
Unauthorized users view RSS feeds for courses or activities they shouldn't have access to, potentially learning about internal organizational activities.
If Mitigated
Limited exposure of non-sensitive RSS feed content with minimal impact on system integrity.
🎯 Exploit Status
Exploitation requires knowledge of RSS feed URLs but no authentication; simple HTTP requests can test for vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Moodle security releases for MDL-84499 fix
Vendor Advisory: https://moodle.org/security/
Restart Required: No
Instructions:
1. Check Moodle version. 2. Apply security patch from Moodle git repository for MDL-84499. 3. Update to latest Moodle version if available. 4. No server restart needed for PHP code changes.
🔧 Temporary Workarounds
Disable RSS feeds
allTemporarily disable RSS functionality in Moodle to prevent unauthorized access
Edit Moodle config.php: $CFG->enablerssfeeds = false;
Restrict RSS access via web server
linuxUse web server configuration to restrict access to RSS feed URLs
Apache: Use .htaccess to require authentication for /rss/ paths
Nginx: Add location blocks to restrict /rss/ access
🧯 If You Can't Patch
- Disable RSS feeds completely in Moodle administration
- Implement web application firewall rules to block unauthorized RSS feed requests
🔍 How to Verify
Check if Vulnerable:
Attempt to access RSS feed URLs without authentication; if accessible, system is vulnerable.Check Version:
Check Moodle version via admin interface or config.php: $CFG->versionVerify Fix Applied:
After patching, attempt same unauthorized RSS access; should receive permission denied error.📡 Detection & Monitoring
Log Indicators:
- Unauthenticated requests to /rss/ endpoints in web server logs
- 403 errors for RSS feeds after fix implementation
Network Indicators:
- HTTP GET requests to RSS feed URLs from unauthenticated IPs
SIEM Query:
web_access_logs WHERE url_path LIKE '%/rss/%' AND auth_status = 'unauthenticated'