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CVE-2026-65658

Microsoft SharePoint Server Remote Code Execution Vulnerability

Published: Aug 11, 2026Updated: Aug 13, 2026 Sources: CVE List NVDCWE-502
8.8HIGH
NVD MITRE
EPSS Score
1.4%
Top 29.9%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

Description

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

In plain language

AI Act now

CVE-2026-65658 is a Microsoft SharePoint Server flaw where an attacker who has a valid SharePoint login can send specially crafted data to run malicious code on the server; you should patch if you run SharePoint, because it’s a remote code execution risk.

Executive summary

CVE-2026-65658 is a remote code execution vulnerability in Microsoft SharePoint Server caused by insecure handling of received data structures (untrusted deserialization), enabling an authenticated attacker to execute arbitrary code on the server without user interaction.

If affected, business impact
Full server takeoverMalware installationService disruptionSensitive data theft risk

What to do now

  1. Check which Microsoft SharePoint Server edition and version you run (2016, 2019, Subscription Edition, or the general “SharePoint Server”) and confirm whether you have the fixed build listed below.
  2. Update Microsoft SharePoint Server to the fixed versions: 16.0.19725.20522 (SharePoint Server and Subscription Edition), 16.0.5565.1001 (SharePoint Enterprise Server 2016), or 16.0.10417.20198 (SharePoint Server 2019).
  3. If you can’t patch right away, temporarily restrict who can access SharePoint and tighten network access so fewer systems/users can reach the SharePoint server, and monitor for suspicious logins and unusual activity.
Patch / advisory Usually a quick update

CVSS Vector Breakdown

AV:NAC:LPR:LUI:NS:UC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-502

Affected Products

Microsoft
commercial·US
Microsoft SharePoint Enterprise Server 2016On-premWeb App
Enterprise Software / itsm-monitoring
Microsoft SharePoint Server 2019On-premWeb App
Enterprise Software / itsm-monitoring
Microsoft SharePoint Server Subscription EditionOn-premWeb App
Enterprise Software / collaboration-groupware
sharepoint serverOn-premWeb App
Enterprise Software / collaboration-groupware

Exploitability

Official Patch Available
Is your org exposed to CVE-2026-65658?We can run the check for you — a free external exposure review, no install. Check my exposure

Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

3 techniques
Execution
Initial Access
View detailed technique mapping

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-65658
msrc.microsoft.com
News mentions
2

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