Cyber Defence Digest
Publication Date: 1 May 2026Coverage Period: March – April 2026
This special edition highlights significant Microsoft security vulnerabilities, zero-days, and enterprise security developments affecting Windows, Microsoft 365, Active Directory, SharePoint, Exchange, Azure, and related technologies.
⚠ Microsoft Windows Zero-Day Vulnerabilities
Vulnerability Level: 🔴 CriticalAffected Platform: Windows
How: Multiple zero-day vulnerabilities were exploited before organisations completed security updates.
Impact: Privilege escalation | Endpoint compromise | Lateral movement
Defence: Deploy the latest cumulative security updates, prioritise internet-facing systems, and verify endpoint compliance.
Reference: Microsoft Security Response Center (MSRC)
⚠ Microsoft Office Security Feature Bypass
Vulnerability Level: 🔴 CriticalAffected Platform: Microsoft Office
How: Crafted Office documents bypass security protections and facilitate malicious code execution.
Impact: Endpoint compromise | Malware delivery | User credential theft
Defence: Apply Office updates, restrict untrusted documents, and enable Microsoft Defender Protected View.
Reference: Microsoft Security Update Guide
⚠ Microsoft SharePoint Enterprise Vulnerabilities
Vulnerability Level: 🔴 CriticalAffected Platform: Microsoft SharePoint Server
How: Multiple vulnerabilities affected on-premises SharePoint deployments, increasing exposure of enterprise collaboration platforms.
Impact: Remote code execution | Information disclosure | SharePoint compromise
Defence: Install the latest SharePoint security updates, enable AMSI integration, and monitor IIS and SharePoint logs.
Reference: Microsoft Security Advisory
⚠ Active Directory Privilege Escalation Risks
Vulnerability Level: 🟠 HighAffected Platform: Active Directory
How: Attackers continued exploiting privilege escalation weaknesses and Active Directory Certificate Services (AD CS) misconfigurations.
Impact: Domain compromise | Credential theft | Long-term persistence
Defence: Audit privileged accounts, review AD CS configurations, implement tiered administration, and enforce MFA.
Reference: Microsoft & Security Research Reports
⚠ Microsoft Defender Security Updates
Vulnerability Level: 🟠 HighAffected Platform: Microsoft Defender
How: Security updates resolved vulnerabilities affecting endpoint protection and security components.
Impact: Security control bypass | Reduced endpoint protection | Privilege escalation
Defence: Verify Defender platform updates, maintain cloud-delivered protection, and review endpoint detection alerts.
Reference: Microsoft Defender Security Intelligence
⚠ Microsoft Azure Identity Security
Vulnerability Level: 🟠 HighAffected Platform: Microsoft Azure / Microsoft Entra ID
How: Identity-based attacks continued targeting cloud tenants through credential theft, phishing, and token abuse.
Impact: Cloud account compromise | Business email compromise | Privileged access abuse
Defence: Enforce phishing-resistant MFA, implement Conditional Access policies, monitor risky sign-ins, and review privileged identities.
Reference: Microsoft Entra Security Guidance