CVE-2026-45591: ASP.NET Core Denial of Service Vulnerability

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-09 · updated 2026-09-24
Weakness: CWE-400

Description

Uncontrolled resource consumption in ASP.NET Core allows an unauthorized attacker to deny service over a network.

Affected products

Microsoft .NET: from 8.0.0 before 8.0.28; from 9.0.0 before 9.0.17; from 10.0.0 before 10.0.9 — fixed in 10.0.9, 8.0.28, 9.0.17
Microsoft .NET Core: from 8.0.0 before 8.0.28; from 9.0.0 before 9.0.17; from 10.0.0 before 10.0.9 — fixed in 10.0.9, 8.0.28, 9.0.17
Microsoft Visual Studio 2026 version 18.9: from 18.6.0 before 18.6.3 — fixed in 18.6.3
Microsoft .NET: from 10.0.0 before 10.0.9 — fixed in 10.0.9
Microsoft .NET 8.0: from 8.0.0 before 8.0.28 — fixed in 8.0.28
Microsoft .NET 9.0: from 9.0.0 before 9.0.17 — fixed in 9.0.17
Microsoft ASP.NET Core 10.0: from 10.0 before 10.0.9 — fixed in 10.0.9
Microsoft ASP.NET Core 8.0: from 8.0 before 8.0.28 — fixed in 8.0.28
Microsoft ASP.NET Core 9.0: from 9.0 before 9.0.17 — fixed in 9.0.17
Microsoft Visual Studio 2026 version 18.6: from 18.6.0 before 18.6.3 — fixed in 18.6.3

How to fix

Upgrade to a fixed version: Microsoft .NET 10.0.9, 8.0.28, 9.0.17; Microsoft .NET Core 10.0.9, 8.0.28, 9.0.17; Microsoft Visual Studio 2026 version 18.9 18.6.3; Microsoft .NET 10.0.9; Microsoft .NET 8.0 8.0.28; Microsoft .NET 9.0 9.0.17; Microsoft ASP.NET Core 10.0 10.0.9; Microsoft ASP.NET Core 8.0 8.0.28; Microsoft ASP.NET Core 9.0 9.0.17; Microsoft Visual Studio 2026 version 18.6 18.6.3. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-45591 or the next vulnerability affects your stack