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.
Other vulnerabilities in Microsoft Office SharePoint
See all- CVE-2026-40368High
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
- CVE-2026-40357High
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
- CVE-2026-35439High
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
- CVE-2026-33112High
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
- CVE-2026-33110High
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
- CVE-2026-20951High
Improper input validation in Microsoft Office SharePoint allows an unauthorized attacker to execute code locally.
- CVE-2026-20947High
Improper neutralization of special elements used in an sql command ('sql injection') in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
- CVE-2026-70306Critical
A cross-site scripting vulnerability in Microsoft Office SharePoint allows an unauthorized attacker to perform spoofing over a network.
- CVE-2026-70332Critical
Improper input neutralization during web page generation (cross-site scripting) in Microsoft Office SharePoint allows an unauthorized attacker to perform spoofing over a network.
- CVE-2026-55040CriticalActively exploited
A vulnerability in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over the network due to weak authentication.
Original NVD description (English source)
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.