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CVE-2026-45659: Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability

Microsoft SharePoint Server · in CISA KEV since 2026-07-01

2026-07-01added to KEV

2026-07-04federal remediation due date

76.08%EPSS exploit probability (30 days) 99.5th percentile

8.8 HIGHCVSS 3.1

Knownknown ransomware use

40days from NVD publication to KEV

What it is

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

Required action (CISA)

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.

CWE	CWE-502
CVSS vector	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`
NVD published	2026-05-22 (Analyzed)

Original records: NVD · CISA KEV · JSON: /api/cve/CVE-2026-45659.json · all KEV CVEs

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