CVE-2025-3986
📋 TL;DR
This vulnerability in Apereo CAS 5.2.6 involves inefficient regular expression complexity in the CasConfigurationMetadataServerController.java file, allowing remote attackers to cause denial of service through resource exhaustion. It affects systems running the vulnerable Apereo CAS version with the configuration metadata endpoint exposed. The vulnerability is problematic but not critical, with moderate impact potential.
💻 Affected Systems
- Apereo CAS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete service unavailability due to CPU/memory exhaustion from crafted regex attacks, potentially affecting authentication services for all users.
Likely Case
Degraded performance or intermittent service disruptions under targeted attack, impacting user authentication reliability.
If Mitigated
Minimal impact with proper input validation, rate limiting, and resource monitoring in place.
🎯 Exploit Status
Exploit has been publicly disclosed and can be initiated remotely without authentication. The vulnerability is relatively easy to exploit.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: Yes
Instructions:
1. Check for vendor patches or updates to Apereo CAS 5.2.6. 2. Upgrade to a patched version when available. 3. Restart CAS services after patching.
🔧 Temporary Workarounds
Disable Configuration Metadata Endpoint
allDisable or restrict access to the vulnerable configuration metadata endpoint
Modify CAS configuration to disable cas.server.metadata.enabled or restrict endpoint access
Implement Rate Limiting
allAdd rate limiting to configuration metadata endpoints
Configure web server or application firewall to limit requests to /cas/actuator/configprops endpoint
🧯 If You Can't Patch
- Implement strict input validation and sanitization for the Name parameter
- Deploy WAF rules to detect and block regex complexity attacks
🔍 How to Verify
Check if Vulnerable:
Check if running Apereo CAS 5.2.6 and if configuration metadata endpoint is accessible at /cas/actuator/configpropsCheck Version:
Check CAS version in application logs or via management endpointsVerify Fix Applied:
Verify CAS version is updated beyond 5.2.6 and test endpoint with crafted inputs to ensure no performance degradation📡 Detection & Monitoring
Log Indicators:
- Unusual CPU spikes
- Increased response times for configuration endpoints
- Multiple requests with complex regex patterns
Network Indicators:
- High volume of requests to /cas/actuator/configprops
- Requests with specially crafted Name parameters
SIEM Query:
source="cas-server" AND (uri_path="/actuator/configprops" AND (response_time>5000 OR status=500))