Microsoft’s patch for CVE-2026-45659 in SharePoint is another reminder that collaboration platforms are high-value enterprise targets, not just document storage systems with better branding. The vulnerability is a remote code execution flaw caused by deserialization of untrusted data in Microsoft Office SharePoint and carries a CVSS score of 8.8. Microsoft says an authenticated attacker with only Site Member permissions could exploit it over the network to execute code remotely on a SharePoint Server.

This is especially important because the flaw affects SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Enterprise Server 2016. Even though Microsoft assessed exploitation as less likely, SharePoint has repeatedly been targeted by attackers in the past, and any RCE on an enterprise collaboration platform deserves fast attention. “Authenticated attacker” should not make anyone relax, since compromised user accounts are not exactly rare in the modern identity swamp. 

Organizations running on-premises SharePoint should apply the relevant updates immediately, review exposed SharePoint deployments, verify least-privilege access for site members, and monitor for suspicious activity such as unexpected process execution, unusual file uploads, abnormal authentication patterns, or web shell behavior. SharePoint servers should also be segmented, backed up, and monitored like critical infrastructure, because that is what they are once they hold business documents, workflows, credentials, and internal knowledge. 

The broader lesson is simple: enterprise applications that sit close to identity, documents, and workflows need continuous patching and hardening. A SharePoint RCE can become more than a server compromise. It can expose sensitive files, enable lateral movement, and give attackers a trusted foothold inside the organization. Treating SharePoint as “just a portal” is the kind of optimism attackers keep monetizing.

Microsoft has rolled out updates to fix a remote code execution vulnerability impacting SharePoint that could be exploited by bad actors in attacks without requiring any specialized conditions to be met. The vulnerability, tracked as CVE-2026-45659, carries a CVSS score of 8.8. It has been assigned an important severity. "Deserialization of untrusted data in Microsoft Office SharePoint allows

Source: Microsoft Patches SharePoint RCE Flaw CVE-2026-45659 Across Server Versions via The Hacker News — published 26 May 2026.