CVE-2021-26423
mediumpriority · track · 21EPSS 0.039 · 90 %ileEURUUSEPSS · scored 2026-10-27
.NET Core and Visual Studio Denial of Service Vulnerability
remediations
Vendor fix, mitigation, or workaround guidance, as published by each source.
A vendor fix is available.
- Fixed.NET 5.0msrc_csaf
5.0.9:Security Update:https://github.com/dotnet/announcements/issues/194
https://github.com/dotnet/announcements/issues/194 - Fixed.NET Core 2.1msrc_csaf
2.1.30:Security Update:https://github.com/dotnet/announcements/issues/194
https://github.com/dotnet/announcements/issues/194 - Fixed.NET Core 3.1msrc_csaf
3.1.18:Security Update:https://github.com/dotnet/announcements/issues/194
https://github.com/dotnet/announcements/issues/194 - FixedMicrosoft Visual Studio 2017 version 15.9 (includes 15.0 - 15.8)msrc_csaf
15.9.38:Security Update:https://docs.microsoft.com/en-us/visualstudio/releasenotes/vs2017-relnotes
https://docs.microsoft.com/en-us/visualstudio/releasenotes/vs2017-relnotes - FixedMicrosoft Visual Studio 2019 version 16.10 (includes 16.0 - 16.9)msrc_csaf
16.10.5:Security Update:https://docs.microsoft.com/en-us/visualstudio/releases/2019/release-notes-v16.10
https://docs.microsoft.com/en-us/visualstudio/releases/2019/release-notes-v16.10 - FixedMicrosoft Visual Studio 2019 version 16.4 (includes 16.0 - 16.3)msrc_csaf
16.4.25:Security Update:https://docs.microsoft.com/en-us/visualstudio/releases/2019/release-notes-v16.4
https://docs.microsoft.com/en-us/visualstudio/releases/2019/release-notes-v16.4 - FixedMicrosoft Visual Studio 2019 version 16.7 (includes 16.0 – 16.6)msrc_csaf
16.7.18:Security Update:https://docs.microsoft.com/en-us/visualstudio/releases/2019/release-notes-v16.7
https://docs.microsoft.com/en-us/visualstudio/releases/2019/release-notes-v16.7 - FixedMicrosoft Visual Studio 2019 version 16.9 (includes 16.0 - 16.8)msrc_csaf
16.9.10:Security Update:https://docs.microsoft.com/en-us/visualstudio/releases/2019/release-notes-v16.9
https://docs.microsoft.com/en-us/visualstudio/releases/2019/release-notes-v16.9 - FixedPowerShell Core 7.0msrc_csaf
7.0.7:Security Update:https://github.com/PowerShell/Announcements/issues/25
https://github.com/PowerShell/Announcements/issues/25 - FixedPowerShell Core 7.1msrc_csaf
7.1.4:Security Update:https://github.com/PowerShell/Announcements/issues/25
https://github.com/PowerShell/Announcements/issues/25 - FixedVisual Studio 2019 for Mac version 8.10msrc_csaf
8.10.7:Security Update:https://docs.microsoft.com/visualstudio/releasenotes/vs2019-mac-relnotes
https://docs.microsoft.com/visualstudio/releasenotes/vs2019-mac-relnotes
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.3–7.5
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (87)
Products and version ranges known to be affected.
advisories (4)
Vendor and ecosystem advisories describing this.
- msrc_CVE-2021-26423.NET Core and Visual Studio Denial of Service Vulnerability2021-08-10csaf · msrc_csafUS
To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle
- GHSA-rh58-r7jh-xhx3.NET Core Elevation of Privilege Vulnerability2022-10-25ghsa · osvUS
Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 5.0 and .NET Core 3.1. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. A denial of service vulnerability exists in .NET 5.0, .NET Core 3.1 and .NET Core 2.1 where .NET (Core) server applications providing WebSocket endpoints could be tricked into endlessly looping while trying to read a single WebSocket frame. ### Patches * If you're using .NET 5.0, you should download and install Runtime 5.0.9 or SDK 5.0.206 (for Visual Studio 2019 v16.8) or SDK 5.0.303 (for Visual Studio 2019 V16.10) from https://dotnet.microsoft.com/download/dotnet-core/5.0. * If you're using .NET Core 3.1, you should download and install Runtime 3.1.18 or SDK 3.1.118 (for Visual Studio 2019 v16.4) or 3.1.412 (for Visual Studio 2019 v16.7 or later) from https://dotnet.microsoft.com/download/dotnet-core/3.1. * If you're using .NET Core 2.1, you should download and install Runtime 2.1.29 or SDK 2.1.525 (for Visual Studio 2019 v15.9) or 2.1.817 from https://dotnet.microsoft.com/download/dotnet-core/2.1. #### Other Details - Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/194 - An Issue for this can be found at https://github.com/dotnet/runtime/issues/57175 - MSRC details for this can be found at https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-26423
- BIT-dotnet-2021-26423.NET Core and Visual Studio Denial of Service Vulnerability2024-03-06vendor · osvUS
.NET Core and Visual Studio Denial of Service Vulnerability
- BIT-dotnet-sdk-2021-26423.NET Core and Visual Studio Denial of Service Vulnerability2024-03-06vendor · osvUS
.NET Core and Visual Studio Denial of Service Vulnerability
also known as (7)
Other names and identifiers for this entity.
- CNNVD-202108-847cnnvd
- EUVD-2022-7160enisa_euvd
- BDU:2021-04773fstec_bdu
- GHSA-rh58-r7jh-xhx3enisa_euvd
- BIT-dotnet-2021-26423osv
- BIT-dotnet-sdk-2021-26423osv
- GHSA-rh58-r7jh-xhx3osv
sources
Which sources assert this record, and when.
references (12)
External citations — patches, advisories, analysis.
- https://access.redhat.com/security/cve/cve-2021-26423cnnvd
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26423cnnvd
- https://packetstormsecurity.com/files/163799/Red-Hat-Security-Advisory-2021-3142-01.htmlcnnvd
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26423cnnvd
- https://vigilance.fr/vulnerability/Microsoft-Visual-Studio-vulnerabilities-of-August-2021-36113cnnvd
- https://www.auscert.org.au/bulletins/ESB-2021.2729cnnvd
- https://www.auscert.org.au/bulletins/ESB-2021.2753cnnvd
- https://www.cybersecurity-help.cz/vdb/SB2021081011cnnvd
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