What’s Vulnerable › Vulnerabilities

CVE-2026-69304: ASP.NET Core Denial of Service Vulnerability

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-08 · updated 2026-10-31
• Weakness: CWE-409

Description

Improper handling of highly compressed data (data amplification) in ASP.NET Core allows an unauthorized attacker to deny service over a network.

Affected products

• Microsoft .NET: from 8.0.0 before 8.0.31; from 9.0.0 before 9.0.20; from 10.0.0 before 10.0.12 — fixed in 8.0.31, 9.0.20, 10.0.12
• 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; from 11.0.0 (excl.); 11.0-rc1 — fixed in 8.0.28, 9.0.17, 10.0.9
• Microsoft Visual Studio 2022 version 17.14: from 17.14.0 before 17.14.40 — fixed in 17.14.40
• Microsoft Visual Studio 2026 version 18.9: from 18.9.0 before 18.9.3 — fixed in 18.9.3
• Microsoft .NET 10.0 runtime: from 10.0.0 before 10.0.12 — fixed in 10.0.12
• Microsoft .NET 8.0 runtime: from 8.0.0 before 8.0.31 — fixed in 8.0.31
• Microsoft .NET 9.0 runtime: from 9.0.0 before 9.0.20 — fixed in 9.0.20
• Microsoft ASP.NET Core 10.0: from 10.0 before 10.0.12 — fixed in 10.0.12
• Microsoft ASP.NET Core 11.0: from 11.0 before 11.0 RC1 — fixed in 11.0 RC1
• Microsoft ASP.NET Core 8.0: from 8.0 before 8.0.31 — fixed in 8.0.31
• Microsoft ASP.NET Core 9.0: from 9.0 before 9.0.20 — fixed in 9.0.20
• Microsoft Visual Studio 2022 version 17.14: from 17.14.0 before 17.14.40 — fixed in 17.14.40
• Microsoft Visual Studio 2026 version 18.9: from 18.9.0 before 18.9.3 — fixed in 18.9.3

How to fix

Upgrade to a fixed version: Microsoft .NET 8.0.31, 9.0.20, 10.0.12; Microsoft .NET Core 8.0.28, 9.0.17, 10.0.9; Microsoft Visual Studio 2022 version 17.14 17.14.40; Microsoft Visual Studio 2026 version 18.9 18.9.3; Microsoft .NET 10.0 runtime 10.0.12; Microsoft .NET 8.0 runtime 8.0.31; Microsoft .NET 9.0 runtime 9.0.20; Microsoft ASP.NET Core 10.0 10.0.12; Microsoft ASP.NET Core 11.0 11.0 RC1; Microsoft ASP.NET Core 8.0 8.0.31; Microsoft ASP.NET Core 9.0 9.0.20; Microsoft Visual Studio 2022 version 17.14 17.14.40. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69304

Get alerted when CVE-2026-69304 or the next vulnerability affects your stack