CVE-2026-69304ImportantRevised 25 Sep
ASP.NET Core Denial of Service Vulnerability
Assessment
Improper handling of highly compressed data (data amplification) in ASP.NET Core allows an unauthorized attacker to deny service over a network.
- Severity
- Important
- CVSS base score
- 5.9CVSS:3.1/
AV:N/ AC:H/ PR:N/ UI:N/ S:U/ C:N/ I:N/ A:H/ E:U/ RL:O/ RC:C - Impact
- Denial of Service
- EPSS, next 30 days
- 0.9%Higher than 57.9% of scored CVEs · FIRST model run 26 Sep 2026 · about EPSS
- Exploitability
- Exploitation Less Likely
- Publicly disclosed
- No
- Customer action
- Required: apply the update
- Component
- ASP.NET Core
- Weakness
- CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)
- Issued by
- Microsoft
- Published
- 8 Sep 2026 · September 2026
- Last revised
- 25 Sep 2026Security Updates table updated provide links to the KB articles and download center updates. Microsoft recommends installing the updates.
Updates that fix it
3 KBs| KB | Type | Restart | Applies to | Other CVEs |
|---|---|---|---|---|
| KB5126104 | Security Update | Required | .NET 8.0 installed on Windows, ASP.NET Core 8.0 | All CVEs in KB5126104 |
| KB5126105 | Security Update | Required | .NET 9.0 installed on Windows, ASP.NET Core 9.0 | All CVEs in KB5126105 |
| KB5126106 | Security Update | Required | .NET 10.0 installed on Windows, ASP.NET Core 10.0 | All CVEs in KB5126106 |
Affected products
Developer Tools9 affected products
- .NET 10.0 installed on Windows
- .NET 8.0 installed on Windows
- .NET 9.0 installed on Windows
- ASP.NET Core 10.0
- ASP.NET Core 11.0
- ASP.NET Core 8.0
- ASP.NET Core 9.0
- Microsoft Visual Studio 2022 version 17.14
- Microsoft Visual Studio 2026 version 18.9