CVE-2026-1554
📋 TL;DR
This XML Injection vulnerability in Drupal CAS Server allows attackers to manipulate XPath queries to escalate privileges. It affects Drupal sites using the CAS Server module for centralized authentication. Attackers could gain unauthorized access to sensitive data or administrative functions.
💻 Affected Systems
- Drupal Central Authentication System (CAS) Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full administrative access to the Drupal site, allowing complete system compromise, data theft, or site defacement.
Likely Case
Privilege escalation to gain access to restricted content or user accounts beyond intended permissions.
If Mitigated
Limited impact with proper input validation and least privilege access controls in place.
🎯 Exploit Status
Requires understanding of XPath injection techniques and CAS Server implementation details.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.0.3 or 2.1.2
Vendor Advisory: https://www.drupal.org/sa-contrib-2026-007
Restart Required: No
Instructions:
1. Update CAS Server module to version 2.0.3 or 2.1.2 via Drupal's update manager. 2. Clear Drupal caches. 3. Verify module functionality.
🔧 Temporary Workarounds
Disable CAS Server Module
linuxTemporarily disable the vulnerable module until patching is possible
drush pm-disable cas_server
Implement Input Validation
allAdd custom input validation for XML/XPath inputs in CAS authentication
🧯 If You Can't Patch
- Implement network segmentation to isolate CAS Server from critical systems
- Enable detailed logging and monitoring for CAS authentication attempts
🔍 How to Verify
Check if Vulnerable:
Check CAS Server module version in Drupal admin interface or via drush: drush pm-list | grep cas_serverCheck Version:
drush pm-list --fields=name,version | grep cas_serverVerify Fix Applied:
Confirm module version is 2.0.3 or higher (for 2.0.x branch) or 2.1.2 or higher (for 2.1.x branch)📡 Detection & Monitoring
Log Indicators:
- Unusual XML payloads in authentication requests
- Failed authentication attempts with malformed XML
- Unexpected privilege changes in user accounts
Network Indicators:
- XML payloads containing XPath injection patterns in CAS authentication traffic
SIEM Query:
source="drupal" AND ("cas_server" OR "cas authentication") AND ("xml" OR "xpath") AND ("injection" OR "malformed")