Microsoft · Security update · April 21, 2026

KB5091596: April 2026 security update

KB5091596, released April 21, 2026, fixes 1 CVE in ASP.NET Core 10.0. None of them is reported as exploited. Patch Radar priority: High.

High
CVEs closed
1
None rated Critical
Exploited
0
None reported
Exploitation more likely
0
Vendor assessment
Highest EPSS
0.1121
95th percentile

Applies to

CVEs this fix closes

PriorityCVEComponentImpactCVSSEPSSExploitation
High CVE-2026-40372 ASP.NET Core Elevation of Privilege 9.1 0.1121 Exploitation Less Likely
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