CVE intelligenceCISA KEV

CVE-2026-58644

Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

Published Jul 14, 2026Sources checked Nov 12, 2026

9.8CRITICALCVSS out of 10

What this means

Actively exploited

CISA lists CVE-2026-58644 in its Known Exploited Vulnerabilities catalog, which means exploitation has been observed. The entry applies to Microsoft SharePoint.

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.

Public exploit: Not collected.

Microsoft Security Response Center: Exploitation reported by Microsoft Security Response Center (2026-07-15)
Microsoft exploitation status: Exploited:Yes

What to do next

Remediation and response

Review the linked vendor advisory and apply the mitigation or fixed release for your affected product.

Microsoft Security Response Center guidance

Vendor revision: Jul 15, 2026

Install KB5002880. Install KB5002874. Install KB5002873.

Vendor-listed releases

16.0.5556.1005
16.0.10417.20153
16.0.19725.20384

CISA KEVListedObserved exploitation

EPSS15.9%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors1Source-linked actor relationships

Overview

What is CVE-2026-58644?

Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.

Source: NVD

Reported activity: Microsoft exploitation status: Exploited:Yes
Microsoft Security Response Center · Published Jul 15, 2026

CISA says: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 catalog due date Jul 19, 2026