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CVE-2026-58644

Critical 9.8 Exploited in the wild (KEV)

Confirmed active exploitation — CISA KEV catalog

Name
Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
Added to catalog
Remediation due date (US federal)
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.

Description

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

Metrics

CVSS 3.1
9.8 (CRITICAL) Score source: CNA CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS — exploit probability
16% (percentile: 97) as of 1 November 2026
CWE
CWE-502

Affected products

microsoft: sharepoint server

References