All vulnerabilities
CVE-2026-58644

Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

Microsoft SharePointApplications & CMS
Open in ThreatlineRecord JSON
CVSS
9.8Critical
ExploitationExploited in the wildAdded to KEV 16 Jul 2026CISA KEV
Exploit odds (EPSS)15.9%Chance of exploitation activity in the next 30 days, higher than 96% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in16.0.5556.1005Also 16.0.10417.20153, 16.0.19725.20384CVE List
Federal deadline19 Jul 2026Remediation due date for US federal agenciesCISA KEV
CISA required actionApply 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 KEV
Patching is not enoughCISA requires federal agencies to look for signs of compromise on affected systems, not only patch (forensic triage under BOD 26-04). Treat exposed systems as possibly compromised. CISA guidance

What fixes it

  • 16.0.5556.1005Microsoft SharePoint Enterprise Server 2016CVE List
  • 16.0.10417.20153Microsoft SharePoint Server 2019CVE List
  • 16.0.19725.20384Microsoft SharePoint Server Subscription EditionCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Timeline

  1. 14 Jul 2026, 17:05 UTCPublishedCVE List
  2. 16 Jul 2026Added to CISA KEVCISA KEV

Public exploit code and templates 1

  • Scanner templateMicrosoft SharePoint Server - WS-Federation BinaryFormatter Deserialization RCENuclei

Listed so defenders can prioritize. Threatline links to the source and does not host exploit code.

Description

Microsoft SharePoint contains a deserialization of untrusted data vulnerability that allows an unauthorized attacker to execute code over a network.

Text from CVE List

Affected versions 3

  • Microsoft SharePoint Enterprise Server 2016affected: 16.0.0 before 16.0.5556.1005CVE List
  • Microsoft SharePoint Server 2019affected: 16.0.0 before 16.0.10417.20153CVE List
  • Microsoft SharePoint Server Subscription Editionaffected: 16.0.0 before 16.0.19725.20384CVE List

References 3