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Findings

CVE-2026-45659

Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability

Published May 22, 2026 · updated Jul 23, 2026 · Microsoft SharePoint Server

Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a network.

Timeline

Detection, updates, and resolution for this record.

  1. May 22, 2026 · Catalog

    Detected

    Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a network.

  2. Jul 1, 2026 · CISA KEV

    Known exploited

    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

  3. Jul 4, 2026 · CISA KEV

    Remediation due

    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

  4. Jul 23, 2026 · Catalog

    Updated

    Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a network.

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 Jul 4, 2026

Affected

  • cpe microsoft/sharepoint serverversion unspecified
  • cpe microsoft/sharepoint server2016
  • cpe microsoft/sharepoint server2019
  • vendor Microsoft SharePoint Serverversion unspecified

Sources

  • CISA KEVCVE-2026-45659

    Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a network.

    cisa.gov
  • CVE.orgCVE-2026-45659

    Official CVE identifier

    cve.org
  • FIRST EPSSCVE-2026-45659

    30-day exploitation probability 2.7%

    first.org
  • NIST NVDCVE-2026-45659

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

    nvd.nist.gov

References