Actively exploited
Listed in CISA’s Known Exploited Vulnerabilities catalog since July 1, 2026.
CVE-2026-45659
Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability
Microsoft · SharePoint Server
Published July 21, 2026
What happened
Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a network.
What it means for your business
Microsoft SharePoint Server is listed in CISA's Known Exploited Vulnerabilities catalog (CVE-2026-45659). Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a network. CISA remediation due date: 2026-07-04. PremierePC tracks KEV alerts for Upstate SC businesses — patch or open a ticket if you need help verifying exposure.
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.
CISA due date: July 4, 2026
Sources
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