# CVE-2021-26423: .NET Core and Visual Studio Denial of Service Vulnerability

CVE-2021-26423 is fixed in 19 products on 1 platform, first by RHSA-2021:3142, released August 11, 2021. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-26423
- Priority: High
- CVSS: 7.5 (Important)
- EPSS: 0.0390
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Vendor exploitability assessment: Exploitation Less Likely
- Published: Aug 10, 2021
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26423

## Description

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.  New versions of .NET that address security vulnerabilities are now available. The updated versions are .NET SDK 5.0.206 and .NET Runtime 5.0.9.  Security Fix(es):  * dotnet: ASP.NET Core WebSocket frame processing DoS (CVE-2021-26423)  * dotnet: Dump file created world-readable (CVE-2021-34485)  * dotnet: ASP.NET Core JWT token logging (CVE-2021-34532)  For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | aspnetcore-runtime-3.1 RHEL 8 | 0:3.1.18-1.el8_4 | [RHSA-2021:3142](https://patchblox.com/security/data/fix/linux/rhsa-2021-3142.md) | Aug 11, 2021 |
| Linux | aspnetcore-runtime-3.1 ol 8 | 0:3.1.18-1.0.1.el8_4 | [ELSA-2021-3142](https://patchblox.com/security/data/fix/linux/elsa-2021-3142.md) | Aug 13, 2021 |
| Linux | aspnetcore-runtime-5.0 RHEL 8 | 0:5.0.9-1.el8_4 | [RHSA-2021:3148](https://patchblox.com/security/data/fix/linux/rhsa-2021-3148.md) | Aug 12, 2021 |
| Linux | aspnetcore-runtime-5.0 ol 8 | 0:5.0.9-1.0.1.el8_4 | [ELSA-2021-3148](https://patchblox.com/security/data/fix/linux/elsa-2021-3148.md) | Aug 13, 2021 |
| Linux | aspnetcore-targeting-pack-3.1 RHEL 8 | 0:3.1.18-1.el8_4 | [RHSA-2021:3142](https://patchblox.com/security/data/fix/linux/rhsa-2021-3142.md) | Aug 11, 2021 |
| Linux | aspnetcore-targeting-pack-3.1 ol 8 | 0:3.1.18-1.0.1.el8_4 | [ELSA-2021-3142](https://patchblox.com/security/data/fix/linux/elsa-2021-3142.md) | Aug 13, 2021 |
| Linux | aspnetcore-targeting-pack-5.0 RHEL 8 | 0:5.0.9-1.el8_4 | [RHSA-2021:3148](https://patchblox.com/security/data/fix/linux/rhsa-2021-3148.md) | Aug 12, 2021 |
| Linux | aspnetcore-targeting-pack-5.0 ol 8 | 0:5.0.9-1.0.1.el8_4 | [ELSA-2021-3148](https://patchblox.com/security/data/fix/linux/elsa-2021-3148.md) | Aug 13, 2021 |
| Linux | dotnet RHEL 8 | 0:5.0.206-1.el8_4 | [RHSA-2021:3148](https://patchblox.com/security/data/fix/linux/rhsa-2021-3148.md) | Aug 12, 2021 |
| Linux | dotnet ol 8 | 0:5.0.206-1.0.1.el8_4 | [ELSA-2021-3148](https://patchblox.com/security/data/fix/linux/elsa-2021-3148.md) | Aug 13, 2021 |
| Linux | dotnet-apphost-pack-3.1 RHEL 8 | 0:3.1.18-1.el8_4 | [RHSA-2021:3142](https://patchblox.com/security/data/fix/linux/rhsa-2021-3142.md) | Aug 11, 2021 |
| Linux | dotnet-apphost-pack-3.1 ol 8 | 0:3.1.18-1.0.1.el8_4 | [ELSA-2021-3142](https://patchblox.com/security/data/fix/linux/elsa-2021-3142.md) | Aug 13, 2021 |
| Linux | dotnet-apphost-pack-5.0 RHEL 8 | 0:5.0.9-1.el8_4 | [RHSA-2021:3148](https://patchblox.com/security/data/fix/linux/rhsa-2021-3148.md) | Aug 12, 2021 |
| Linux | dotnet-apphost-pack-5.0 ol 8 | 0:5.0.9-1.0.1.el8_4 | [ELSA-2021-3148](https://patchblox.com/security/data/fix/linux/elsa-2021-3148.md) | Aug 13, 2021 |
| Linux | dotnet-host RHEL 8 | 0:5.0.9-1.el8_4 | [RHSA-2021:3148](https://patchblox.com/security/data/fix/linux/rhsa-2021-3148.md) | Aug 12, 2021 |
| Linux | dotnet-host ol 8 | 0:5.0.9-1.0.1.el8_4 | [ELSA-2021-3148](https://patchblox.com/security/data/fix/linux/elsa-2021-3148.md) | Aug 13, 2021 |
| Linux | dotnet-hostfxr-3.1 RHEL 8 | 0:3.1.18-1.el8_4 | [RHSA-2021:3142](https://patchblox.com/security/data/fix/linux/rhsa-2021-3142.md) | Aug 11, 2021 |
| Linux | dotnet-hostfxr-3.1 ol 8 | 0:3.1.18-1.0.1.el8_4 | [ELSA-2021-3142](https://patchblox.com/security/data/fix/linux/elsa-2021-3142.md) | Aug 13, 2021 |
| Linux | dotnet-hostfxr-5.0 RHEL 8 | 0:5.0.9-1.el8_4 | [RHSA-2021:3148](https://patchblox.com/security/data/fix/linux/rhsa-2021-3148.md) | Aug 12, 2021 |
| Linux | dotnet-hostfxr-5.0 ol 8 | 0:5.0.9-1.0.1.el8_4 | [ELSA-2021-3148](https://patchblox.com/security/data/fix/linux/elsa-2021-3148.md) | Aug 13, 2021 |
| Linux | dotnet-runtime-3.1 RHEL 8 | 0:3.1.18-1.el8_4 | [RHSA-2021:3142](https://patchblox.com/security/data/fix/linux/rhsa-2021-3142.md) | Aug 11, 2021 |
| Linux | dotnet-runtime-3.1 ol 8 | 0:3.1.18-1.0.1.el8_4 | [ELSA-2021-3142](https://patchblox.com/security/data/fix/linux/elsa-2021-3142.md) | Aug 13, 2021 |
| Linux | dotnet-runtime-5.0 RHEL 8 | 0:5.0.9-1.el8_4 | [RHSA-2021:3148](https://patchblox.com/security/data/fix/linux/rhsa-2021-3148.md) | Aug 12, 2021 |
| Linux | dotnet-runtime-5.0 ol 8 | 0:5.0.9-1.0.1.el8_4 | [ELSA-2021-3148](https://patchblox.com/security/data/fix/linux/elsa-2021-3148.md) | Aug 13, 2021 |
| Linux | dotnet-sdk-3.1 RHEL 8 | 0:3.1.118-1.el8_4 | [RHSA-2021:3142](https://patchblox.com/security/data/fix/linux/rhsa-2021-3142.md) | Aug 11, 2021 |
| Linux | dotnet-sdk-3.1 ol 8 | 0:3.1.118-1.0.1.el8_4 | [ELSA-2021-3142](https://patchblox.com/security/data/fix/linux/elsa-2021-3142.md) | Aug 13, 2021 |
| Linux | dotnet-sdk-5.0 RHEL 8 | 0:5.0.206-1.el8_4 | [RHSA-2021:3148](https://patchblox.com/security/data/fix/linux/rhsa-2021-3148.md) | Aug 12, 2021 |
| Linux | dotnet-sdk-5.0 ol 8 | 0:5.0.206-1.0.1.el8_4 | [ELSA-2021-3148](https://patchblox.com/security/data/fix/linux/elsa-2021-3148.md) | Aug 13, 2021 |
| Linux | dotnet-targeting-pack-3.1 RHEL 8 | 0:3.1.18-1.el8_4 | [RHSA-2021:3142](https://patchblox.com/security/data/fix/linux/rhsa-2021-3142.md) | Aug 11, 2021 |
| Linux | dotnet-targeting-pack-3.1 ol 8 | 0:3.1.18-1.0.1.el8_4 | [ELSA-2021-3142](https://patchblox.com/security/data/fix/linux/elsa-2021-3142.md) | Aug 13, 2021 |
| Linux | dotnet-targeting-pack-5.0 RHEL 8 | 0:5.0.9-1.el8_4 | [RHSA-2021:3148](https://patchblox.com/security/data/fix/linux/rhsa-2021-3148.md) | Aug 12, 2021 |
| Linux | dotnet-targeting-pack-5.0 ol 8 | 0:5.0.9-1.0.1.el8_4 | [ELSA-2021-3148](https://patchblox.com/security/data/fix/linux/elsa-2021-3148.md) | Aug 13, 2021 |
| Linux | dotnet-templates-3.1 RHEL 8 | 0:3.1.118-1.el8_4 | [RHSA-2021:3142](https://patchblox.com/security/data/fix/linux/rhsa-2021-3142.md) | Aug 11, 2021 |
| Linux | dotnet-templates-3.1 ol 8 | 0:3.1.118-1.0.1.el8_4 | [ELSA-2021-3142](https://patchblox.com/security/data/fix/linux/elsa-2021-3142.md) | Aug 13, 2021 |
| Linux | dotnet-templates-5.0 RHEL 8 | 0:5.0.206-1.el8_4 | [RHSA-2021:3148](https://patchblox.com/security/data/fix/linux/rhsa-2021-3148.md) | Aug 12, 2021 |
| Linux | dotnet-templates-5.0 ol 8 | 0:5.0.206-1.0.1.el8_4 | [ELSA-2021-3148](https://patchblox.com/security/data/fix/linux/elsa-2021-3148.md) | Aug 13, 2021 |
| Linux | netstandard-targeting-pack-2.1 RHEL 8 | 0:5.0.206-1.el8_4 | [RHSA-2021:3148](https://patchblox.com/security/data/fix/linux/rhsa-2021-3148.md) | Aug 12, 2021 |
| Linux | netstandard-targeting-pack-2.1 ol 8 | 0:5.0.206-1.0.1.el8_4 | [ELSA-2021-3148](https://patchblox.com/security/data/fix/linux/elsa-2021-3148.md) | Aug 13, 2021 |

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