VTA-004506 – Wormable RCE Vulnerability in Windows LDAP Poses Critical Security Risk

A newly disclosed remote code execution (RCE) vulnerability in Windows Lightweight Directory Access Protocol (LDAP), CVE-2025-21376, presents a severe security threat, capable of spreading autonomously across networks without user interaction.

Classified as critical with a CVSS score of 8.1/7.1, this flaw arises from race conditions, integer underflow, and heap-based buffer overflow vulnerabilities. Attackers can exploit it through specially crafted network requests, gaining unauthorized control over systems without requiring authentication or user interaction. Despite its high attack complexity, the potential for large-scale exploitation makes this vulnerability a major concern.

Microsoft warns that exploitation is highly likely, drawing comparisons to WannaCry (2017) due to its “wormable” nature. Administrators must act swiftly by applying the latest security patches, restricting LDAP access, enhancing network monitoring, and reviewing incident response strategies to mitigate this growing threat.

Severity:
Medium

Attack Surface:
Cloud Service, Infrastructure, Remote Access Service, Supply Chain (Third-party vendors)

Tactics:
Collection, Credential Access, Exfiltration, Initial Access, Lateral Movement

Techniques:
T1496 – Resource Hijacking
T1210 – Exploitation of Remote Services
T1133 – External Remote Services
T1573 – Encrypted Channel
T1486 – Data Encrypted for Impact

References:
1. https://www.securityweek.com/microsoft-patches-wormable-windows-flaw-and-file-deleting-zero-day/

SuperPRO’s Threat Countermeasures Procedures: 
1. Prioritize patching all Windows servers running LDAP services, especially domain controllers.
2. Ensure all dependent systems and third-party software are updated to prevent indirect exploitation.
3. Enforce LDAP over SSL (LDAPS) to prevent interception or manipulation of LDAP requests.
4. Monitor and restrict lateral movement by segmenting networks and enforcing least privilege access.
5. Backup critical data regularly and store copies offline to prevent ransomware impact.

Contributed by: Carmen