A critical zero-day vulnerability has been discovered in Microsoft SharePoint, which is currently unpatched and actively exploited in the wild. This vulnerability has led to breaches in over 75 company servers, indicating a widespread and impactful attack campaign. Although specific technical details and affected SharePoint versions are not provided, the nature of the vulnerability being a zero-day implies that attackers are exploiting an unknown or unmitigated flaw in SharePoint's codebase. SharePoint is widely used for collaboration, document management, and intranet portals, often containing sensitive corporate data. Exploitation of this zero-day could allow attackers to execute arbitrary code, escalate privileges, or bypass authentication controls, leading to unauthorized access to confidential information, data exfiltration, and potential lateral movement within affected networks. The lack of an available patch increases the risk and urgency for organizations to implement interim mitigations. The breach of 75+ company servers underscores the active exploitation and the threat's severity. Given SharePoint's integration with Microsoft ecosystems and its deployment in many enterprise environments, this vulnerability poses a significant risk to organizations relying on this platform for critical business operations.

For European organizations, the impact of this SharePoint zero-day is substantial. Many European enterprises, government agencies, and public sector organizations utilize Microsoft SharePoint for internal collaboration and document management, often storing sensitive personal data protected under GDPR. A successful exploitation could lead to unauthorized disclosure of personal and corporate data, resulting in regulatory penalties, reputational damage, and operational disruption. The breach of multiple servers indicates that attackers may gain persistent access, enabling espionage, intellectual property theft, or ransomware deployment. The critical nature of the vulnerability and its active exploitation heighten the risk of widespread compromise across sectors such as finance, healthcare, manufacturing, and government. Additionally, the unpatched status means organizations cannot rely on vendor fixes and must adopt immediate defensive measures. The potential for data breaches also raises concerns about compliance with European data protection laws and incident reporting requirements.

Given the absence of an official patch, European organizations should take the following specific measures: 1) Conduct immediate audits of SharePoint server logs and network traffic for indicators of compromise or unusual activity, focusing on the timeframe since the vulnerability was first reported. 2) Restrict external and internal access to SharePoint servers by implementing network segmentation and applying strict firewall rules to limit exposure. 3) Enforce multi-factor authentication (MFA) for all SharePoint access to reduce the risk of credential abuse. 4) Temporarily disable or limit SharePoint features that allow file uploads or custom code execution, which may be vectors for exploitation. 5) Apply enhanced monitoring and alerting for anomalous behaviors related to SharePoint services, including privilege escalations and unexpected process executions. 6) Prepare incident response plans tailored to SharePoint compromise scenarios, including data backup verification and containment strategies. 7) Engage with Microsoft and trusted cybersecurity vendors for threat intelligence updates and to prioritize patch deployment once available. 8) Educate IT and security teams about this zero-day to ensure rapid detection and response capabilities.