What’s Vulnerable › Vulnerabilities

CVE-2020-1597: ASP.NET Core Denial of Service Vulnerability

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 6.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-08-17 · updated 2026-06-17

Description

A denial of service vulnerability exists when ASP.NET Core improperly handles web requests. An attacker who successfully exploited this vulnerability could cause a denial of service against an ASP.NET Core web application. The vulnerability can be exploited remotely, without authentication. A remote unauthenticated attacker could exploit this vulnerability by issuing specially crafted requests to the ASP.NET Core application. The update addresses the vulnerability by correcting how the ASP.NET Core web application handles web requests.

Affected products

• Fedoraproject Fedora: 32, 33
• Microsoft .NET Core: 2.1, 3.1
• Microsoft Visual Studio 2017 version 15.9 (includes 15.0 - 15.8): from 15.0 through 15.8
• Microsoft Visual Studio 2019: from 16.0 through 16.3; from 16.5 through 16.6
• Microsoft ASP.NET Core 2.1: from 2.0 before publication — fixed in publication
• Microsoft ASP.NET Core 3.1: from 3.0 before publication — fixed in publication
• Microsoft Visual Studio 2019 version 16.0: from 16.0 before publication — fixed in publication
• Microsoft Visual Studio 2019 version 16.4 (includes 16.0 - 16.3): from 16.0 before publication — fixed in publication
• Microsoft Visual Studio 2019 version 16.7 (includes 16.0 – 16.6): from 16.0.0 before publication — fixed in publication
• Microsoft Visual Studio 2017 version 15.9 (includes 15.0 - 15.8): from 15.9.0 before publication — fixed in publication

How to fix

Upgrade to a fixed version: Microsoft ASP.NET Core 2.1 publication; Microsoft ASP.NET Core 3.1 publication; Microsoft Visual Studio 2019 version 16.0 publication; Microsoft Visual Studio 2019 version 16.4 (includes 16.0 - 16.3) publication; Microsoft Visual Studio 2019 version 16.7 (includes 16.0 – 16.6) publication; Microsoft Visual Studio 2017 version 15.9 (includes 15.0 - 15.8) publication. Check the vendor advisory for mitigations.

References

• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WH5FQ5VT3JGHXFXOETHCTBWJUIAPGHHT/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZW4CBI26KSO3PRL3HLVVISXPPOYUHSXO/
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1597
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WH5FQ5VT3JGHXFXOETHCTBWJUIAPGHHT/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZW4CBI26KSO3PRL3HLVVISXPPOYUHSXO/
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1597

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