CVE-2025-26670
📋 TL;DR
A use-after-free vulnerability in Windows LDAP allows unauthorized attackers to execute arbitrary code remotely over a network. This affects Windows systems running LDAP services, potentially enabling remote code execution without authentication.
💻 Affected Systems
- Windows LDAP Service
📦 What is this software?
Windows 10 1507 by Microsoft
Windows 10 1507 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 21h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 11 22h2 by Microsoft
Windows 11 23h2 by Microsoft
Windows 11 24h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via remote code execution, leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Remote code execution leading to lateral movement within the network, credential harvesting, and privilege escalation.
If Mitigated
Limited impact if network segmentation restricts LDAP traffic and systems are patched promptly.
🎯 Exploit Status
Exploitation requires network access to LDAP service. No authentication needed based on CVE description.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft Security Update Guide for specific KB numbers
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-26670
Restart Required: Yes
Instructions:
1. Apply latest Windows security updates from Microsoft
2. Restart affected systems
3. Verify patch installation via Windows Update history
🔧 Temporary Workarounds
Network Segmentation
allRestrict LDAP traffic to trusted networks only
Configure firewall rules to block LDAP (TCP 389, 636, 3268, 3269) from untrusted networks
LDAP Signing Enforcement
windowsRequire LDAP signing to prevent certain attack vectors
Set registry key: HKLM\SYSTEM\CurrentControlSet\Services\NTDS\Parameters\LDAPServerIntegrity to 2
🧯 If You Can't Patch
- Implement strict network segmentation to isolate LDAP traffic
- Monitor LDAP services for anomalous activity and implement intrusion detection
🔍 How to Verify
Check if Vulnerable:
Check Windows version and patch level against Microsoft advisoryCheck Version:
wmic os get caption, version, buildnumber, csdversionVerify Fix Applied:
Verify security update KB number is installed via Windows Update history📡 Detection & Monitoring
Log Indicators:
- Unusual LDAP connection attempts
- Failed authentication events from unexpected sources
- Process creation events from lsass.exe or LDAP service
Network Indicators:
- Unusual LDAP traffic patterns
- LDAP requests from unexpected IP addresses
- Multiple failed LDAP binds
SIEM Query:
source="windows" AND (event_id=4625 OR event_id=4771) AND process_name="lsass.exe" | stats count by src_ip