Microsoft June 2025 Patch Tuesday: Critical Zero-Day Fixes and 66 Flaws Addressed

Microsoft’s June 2025 Patch Tuesday has arrived, delivering security updates for 66 vulnerabilities, including one actively exploited zero-day and another publicly disclosed flaw. This release is critical for organizations relying on Microsoft products, as it addresses high-severity issues affecting Windows, Office, SharePoint, and other widely used platforms. The updates follow a trend of increasing zero-day exploitation, with attackers targeting unpatched systems within hours of disclosure.

Executive Summary for Security Leaders

The June 2025 Patch Tuesday includes fixes for 66 vulnerabilities, with 10 rated as Critical and 56 as Important. The most urgent patches address CVE-2025-33053 (an actively exploited WebDAV remote code execution flaw) and CVE-2025-33073 (a publicly disclosed Windows SMB privilege escalation vulnerability). These flaws pose immediate risks to enterprise environments, particularly those with internet-facing services or legacy protocols enabled.

Total Patches: 66 (10 Critical, 56 Important)
Zero-Days: 2 (1 actively exploited, 1 publicly disclosed)
Key Products Affected: Windows, Office, SharePoint, Hyper-V, Visual Studio
Urgency: Immediate patching recommended for CVE-2025-33053 and CVE-2025-33073

Technical Breakdown of Critical Vulnerabilities

The actively exploited zero-day, CVE-2025-33053, affects WebDAV implementations and allows remote code execution via crafted URLs. Check Point Research discovered this flaw, which has a CVSS score of 7.8. Attackers can leverage it to gain initial access to systems without authentication, making it particularly dangerous for exposed servers.

The second zero-day, CVE-2025-33073, is a Windows SMB Client privilege escalation vulnerability with a CVSS score of 7.5. While not yet observed in active attacks, its public disclosure increases the likelihood of exploitation. Microsoft recommends enforcing SMB server-side signing via Group Policy as a temporary mitigation for organizations unable to patch immediately.

Vulnerability Distribution by Type (June 2025)
Category	Count	Examples
Remote Code Execution	25	SharePoint, Office, Hyper-V
Elevation of Privilege	13	SMB, Kernel, Installer
Information Disclosure	17	Storage Management Provider

Patching Recommendations and Best Practices

Organizations should prioritize patching internet-facing systems first, particularly those running WebDAV or SMB services. For environments with strict change control, Microsoft provides mitigation guidance in their security advisories. Testing patches in staging environments remains crucial, as some updates may introduce compatibility issues with legacy applications.

For security teams, the following steps are recommended:

Inventory systems running affected components (WebDAV, SMB, Hyper-V)
Apply patches to critical infrastructure within 72 hours
Monitor for signs of exploitation attempts
Review third-party software updates (Adobe, Cisco, SAP) released concurrently

Conclusion

The June 2025 Patch Tuesday addresses significant security risks, with particular attention required for the two zero-day vulnerabilities. Organizations should treat this update cycle with high priority, given the active exploitation of one flaw and the public disclosure of another. Regular patch management remains the most effective defense against these threats.