CISA KEV 01 Jul 2026: 1 exploited flaw in Microsoft

Conceptual illustration: An anonymous envelope and glass video-meeting window connected to a protected server. Headline: EMAIL & COLLABORATION.

AI-generated illustration by CyberShitty. Not a photograph or a document from the organisations named.

On 1 July 2026, CISA added 1 actively exploited vulnerability affecting Microsoft to its Known Exploited Vulnerabilities catalog. If you run any of these products, patch or mitigate now — exploitation is already happening.

CVE-2026-45659Known ransomware useFederal deadline 04 Jul 2026

Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability

Microsoft / SharePoint Server / CWE-502

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.

msrc.microsoft.com · nvd.nist.gov

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Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability