Actively exploited in the wild
Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
Microsoft - SharePoint · Listed in the CISA KEV since 2026-07-16. This indicates confirmed attacks in production environments.
Required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
CVE-2026-58644
CriticalCVSS 9.8KEVExploitation Probability (EPSS)
Elevated risk71th percentile - higher than 71% of all known CVEs
Summary
A deserialization of untrusted data vulnerability in Microsoft Office SharePoint allows an unauthorized attacker to execute code remotely over a network.
Risk Assessment
An attacker could take control of the SharePoint server, access sensitive data, or disrupt services, posing a critical risk to the organization.
Recommendation
Apply the security update provided by Microsoft for SharePoint immediately and restrict network access to the server to trusted sources only.
Original NVD description (English source)
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.