What’s Vulnerable › Vulnerabilities

CVE-2021-31957: ASP.NET Core Denial of Service Vulnerability

• Severity: medium (CVSS 5.0 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 5.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-06-08 · updated 2026-10-07
• Weakness: CWE-400

Description

ASP.NET Core Denial of Service Vulnerability

Affected products

• Fedoraproject Fedora: 33, 34
• Microsoft .NET: from 5.0 through 5.0.6
• Microsoft Corporation .NET Core: from 3.1 through 3.1.15
• Microsoft Visual Studio 2019: from 16.0 through 16.10; 8.10
• Microsoft .NET 5.0: from 5.0.0 before 5.0.7 — fixed in 5.0.7
• Microsoft .NET Core 3.1: from 3.1 before 3.1.16 — fixed in 3.1.16
• Microsoft Visual Studio 2019 version 16.10 (includes 16.0 - 16.9): from 16.10.0 before 16.10.1 — fixed in 16.10.1
• Microsoft Visual Studio 2019 version 16.4 (includes 16.0 - 16.3): from 16.0 before 16.4.23 — fixed in 16.4.23
• Microsoft Visual Studio 2019 version 16.7 (includes 16.0 – 16.6): from 16.0.0 before 16.7.16 — fixed in 16.7.16
• Microsoft Visual Studio 2019 version 16.9 (includes 16.0 - 16.8): from 15.0.0 before 16.9.7 — fixed in 16.9.7
• Microsoft Visual Studio 2019 for Mac version 8.10: from 8.1.0 before 8.10.1 — fixed in 8.10.1

How to fix

Upgrade to a fixed version: Microsoft .NET 5.0 5.0.7; Microsoft .NET Core 3.1 3.1.16; Microsoft Visual Studio 2019 version 16.10 (includes 16.0 - 16.9) 16.10.1; Microsoft Visual Studio 2019 version 16.4 (includes 16.0 - 16.3) 16.4.23; Microsoft Visual Studio 2019 version 16.7 (includes 16.0 – 16.6) 16.7.16; Microsoft Visual Studio 2019 version 16.9 (includes 16.0 - 16.8) 16.9.7; Microsoft Visual Studio 2019 for Mac version 8.10 8.10.1. Check the vendor advisory for mitigations.

References

• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4PRVVLXXQEF4SEJOBV3VRJHGX7YHY2CG/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CVCDYIP4A6DDRT7G6P3ZW6PKNK2DNWJ2/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PMHWHRRYDHKM6BIINW5V7OCSW4SDWB4W/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VMAO4NG2OQ4PCXUQWMNSCMYWLIJJY6UY/
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31957
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4PRVVLXXQEF4SEJOBV3VRJHGX7YHY2CG/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CVCDYIP4A6DDRT7G6P3ZW6PKNK2DNWJ2/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PMHWHRRYDHKM6BIINW5V7OCSW4SDWB4W/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VMAO4NG2OQ4PCXUQWMNSCMYWLIJJY6UY/
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31957

Get alerted when CVE-2021-31957 or the next vulnerability affects your stack