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CVE-2026-65663: Microsoft SharePoint Server Remote Code Execution Vulnerability

highCVSS 8.8CVE-2026-65663
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.

CSIRTS triage

vendor: Microsoftproduct: SharePoint ServerRemote code executionUnsafe deserialization
What
Deserialization of untrusted data in SharePoint Server allows network-based code execution.
Who is affected
Authorized attackers with network access to SharePoint Server deployments.
Urgency
Critical severity (CVSS 8.8) but not currently exploited; immediate remediation is required.
Action
Apply Microsoft security patches for CVE-2026-65663 immediately.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source
Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity
high — CVSS 8.8
Published
2026-08-11
Exploitation
Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-65663

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2026-65663coverage & exploitation statusNVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for Microsoft SharePoint Server

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

More from Microsoft Security Response Center