{"id":"CVE-2021-1723","aliases":["BIT-aspnet-core-2021-1723","GHSA-242j-2gm6-5rwx"],"url":"https://o3.security/vulnerability/CVE-2021-1723","summary":"ASP.NET Core and Visual Studio Denial of Service Vulnerability","details":"A denial-of-service vulnerability exists in the way Kestrel parses HTTP/2 requests. The security update addresses the vulnerability by fixing the way the Kestrel parses HTTP/2 requests. Users are advised to upgrade.","published":"2021-01-12T20:15:34.993Z","modified":"2026-07-08T05:56:49.573599199Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.Server.Kestrel.Core","fixedVersion":"2.1.25"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.linux-arm","fixedVersion":"3.1.11"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.linux-arm","fixedVersion":"5.0.2"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.linux-arm64","fixedVersion":"3.1.11"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.linux-arm64","fixedVersion":"5.0.2"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.linux-musl-arm64","fixedVersion":"3.1.11"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.linux-musl-arm64","fixedVersion":"5.0.2"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.linux-musl-x64","fixedVersion":"3.1.11"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.linux-musl-x64","fixedVersion":"5.0.2"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.linux-x64","fixedVersion":"3.1.11"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.linux-x64","fixedVersion":"5.0.2"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.osx-x64","fixedVersion":"3.1.11"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.osx-x64","fixedVersion":"5.0.2"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.win-arm","fixedVersion":"3.1.11"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.win-arm","fixedVersion":"5.0.2"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.win-arm64","fixedVersion":"3.1.11"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.win-arm64","fixedVersion":"5.0.2"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.win-x64","fixedVersion":"3.1.11"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.win-x64","fixedVersion":"5.0.2"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.win-x86","fixedVersion":"3.1.11"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.win-x86","fixedVersion":"5.0.2"},{"ecosystem":"NuGet","name":"Microsoft.AspNetCore.App.Runtime.linux-musl-arm","fixedVersion":"5.0.2"}],"fix":null,"references":[{"type":"WEB","url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1723"},{"type":"ADVISORY","url":"https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1723"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-1723"},{"type":"WEB","url":"https://github.com/dotnet/announcements/issues/170"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3L27CGRVEWUPELNJOGTCW6GLEDBECB4B"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/RRXHERXW4KR5WCP76UDW5PC7GX3YQLUW"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-08T05:56:49.573599199Z"}}