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KB5123731: what it fixes and who gets it

KB5123731 is a security update from Microsoft's September 2026 release for Microsoft Dynamics 365 Customer Engagement V9.1.

Microsoft data read
1CVEs fixed
0rated Critical
0already exploited
Norestart required

Should you install it?

Yes. It is a routine security update; none of its fixes are rated Critical or reported as exploited. Windows Update installs it automatically on supported home PCs.

If the installation fails or the PC misbehaves afterwards, note the exact error code first: the fix depends on it. Our update troubleshooting guides are linked on this page.

Security fixes in KB5123731

CVETypeCVSSSeverity
CVE-2026-77908Microsoft Dynamics 365 On-Premises Remote Code Execution VulnerabilityRemote Code Execution8.8Important

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