--- id: "CVE-2026-109481" page: "https://infrastack.ai/live/CVE-2026-109481" kind: "vulnerability" aliases: ["CVE-2026-109481", "GHSA-xw2x-23jm-j582"] title: "Microsoft Security Advisory CVE-2026-109481 - ASP.NET Core Elevation of Privilege Vulnerability" severity: "high" cvss: 7.5 epss: null exploited: false status: "open" category: "runtime" products: [{"name": "Microsoft.AspNetCore.App.Runtime.linux-arm", "fixed": ["11.0.0"], "affected": ">= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148", "ecosystem": "nuget"}, {"name": "Microsoft.AspNetCore.App.Runtime.linux-arm64", "fixed": ["11.0.0"], "affected": ">= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148", "ecosystem": "nuget"}, {"name": "Microsoft.AspNetCore.App.Runtime.linux-musl-arm", "fixed": ["11.0.0"], "affected": ">= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148", "ecosystem": "nuget"}, {"name": "Microsoft.AspNetCore.App.Runtime.linux-musl-arm64", "fixed": ["11.0.0"], "affected": ">= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148", "ecosystem": "nuget"}, {"name": "Microsoft.AspNetCore.App.Runtime.linux-musl-x64", "fixed": ["11.0.0"], "affected": ">= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148", "ecosystem": "nuget"}, {"name": "Microsoft.AspNetCore.App.Runtime.linux-x64", "fixed": ["11.0.0"], "affected": ">= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148", "ecosystem": "nuget"}, {"name": "Microsoft.AspNetCore.App.Runtime.osx-arm64", "fixed": ["11.0.0"], "affected": ">= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148", "ecosystem": "nuget"}, {"name": "Microsoft.AspNetCore.App.Runtime.osx-x64", "fixed": ["11.0.0"], "affected": ">= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148", "ecosystem": "nuget"}, {"name": "Microsoft.AspNetCore.App.Runtime.win-arm64", "fixed": ["11.0.0"], "affected": ">= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148", "ecosystem": "nuget"}, {"name": "Microsoft.AspNetCore.App.Runtime.win-x64", "fixed": ["11.0.0"], "affected": ">= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148", "ecosystem": "nuget"}, {"name": "Microsoft.AspNetCore.App.Runtime.win-x86", "fixed": ["11.0.0"], "affected": ">= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148", "ecosystem": "nuget"}] ecosystems: ["nuget"] tags: ["aspnet-core", "blazor", "cwe-352", "dotnet", "runtime", "signalr", "web-apps"] not_affected_if: ["no-blazor-or-signalr", "outside-affected-version-range"] published_at: "2026-11-10T19:18:17+00:00" first_seen_at: "2026-11-10T19:24:25+00:00" updated_at: "2026-11-10T23:35:01+00:00" sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-109481", "first_seen_at": "2026-11-10T19:24:25+00:00"}, {"source": "ghsa", "url": "https://github.com/advisories/GHSA-xw2x-23jm-j582", "first_seen_at": "2026-11-10T23:34:09+00:00"}] exploit_sources: [] --- # Microsoft Security Advisory CVE-2026-109481 - ASP.NET Core Elevation of Privilege Vulnerability Link for people: https://infrastack.ai/live/CVE-2026-109481 (this .md is for agents) A cross-site request to the Blazor/SignalR `/_blazor/refresh` path can bind a victim's signed-in identity to an attacker-owned circuit. An attacker can act as the victim inside a Blazor Server app that accepts this request. _Summary, check and fix written by a model from the sources; labelled as such._ ## Affected - nuget:Microsoft.AspNetCore.App.Runtime.linux-arm affected >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 fixed 11.0.0 - nuget:Microsoft.AspNetCore.App.Runtime.linux-arm64 affected >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 fixed 11.0.0 - nuget:Microsoft.AspNetCore.App.Runtime.linux-musl-arm affected >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 fixed 11.0.0 - nuget:Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 affected >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 fixed 11.0.0 - nuget:Microsoft.AspNetCore.App.Runtime.linux-musl-x64 affected >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 fixed 11.0.0 - nuget:Microsoft.AspNetCore.App.Runtime.linux-x64 affected >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 fixed 11.0.0 - nuget:Microsoft.AspNetCore.App.Runtime.osx-arm64 affected >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 fixed 11.0.0 - nuget:Microsoft.AspNetCore.App.Runtime.osx-x64 affected >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 fixed 11.0.0 - nuget:Microsoft.AspNetCore.App.Runtime.win-arm64 affected >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 fixed 11.0.0 - nuget:Microsoft.AspNetCore.App.Runtime.win-x64 affected >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 fixed 11.0.0 - nuget:Microsoft.AspNetCore.App.Runtime.win-x86 affected >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 fixed 11.0.0 ## How to check - Check the ASP.NET Core runtime version with `dotnet --list-runtimes` and compare it to the affected range `>= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148`. - Check self-contained apps and their `Microsoft.AspNetCore.App.Runtime.*` package references against the same range; a machine-wide runtime update does not replace an embedded runtime. - Confirm whether the app uses Blazor or SignalR endpoints such as `/_blazor/refresh`. ## Fix - Update affected packages and runtimes to `11.0.0` or later. - Rebuild and redeploy self-contained applications. ## Timeline - 2026-11-10T19:24:25+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-109481 - 2026-11-10T23:34:09+00:00 ghsa https://github.com/advisories/GHSA-xw2x-23jm-j582 ## Documents - [advisory] Maintainer's advisory: api.github.com https://api.github.com/repos/dotnet/aspnetcore/security-advisories/GHSA-xw2x-23jm-j582 - [advisory] Maintainer's advisory: github.com https://github.com/dotnet/aspnetcore/security/advisories/GHSA-xw2x-23jm-j582 - [fix] Release: github.com https://github.com/dotnet/aspnetcore/releases/tag/v11.0.0 ## From the sources ## Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core. This advisory provides guidance on updating affected applications and components. The Blazor/SignalR `/_blazor/refresh` path can accept a cross-site request that binds a victim's authenticated principal to an attacker-owned circuit. ## Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/506 ## CVSS Details - **Version:** 3.1 - **Severity:** High - **Score:** 7.5 (base score) - **Vector:** `CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C` - **Weakness:** CWE-352 ## Affected Platforms - **Platforms:** Windows, Linux, macOS - **Architectures:** All ## Affected Packages The tables list affected version ranges and fixed package versions. Runtime and standalone deliveries are listed separately. ### .NET 11.0 - affected runtime packages Package | Affected version | Patched version --- | --- | --- [Microsoft.AspNetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-arm) | >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 | 11.0.0 [Microsoft.AspNetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-arm64) | >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 | 11.0.0 [Microsoft.AspNetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-arm) | >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 | 11.0.0 [Microsoft.AspNetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-arm64) | >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 | 11.0.0 [Microsoft.AspNetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-x64) | >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 | 11.0.0 [Microsoft.AspNetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-x64) | >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 | 11.0.0 [Microsoft.AspNetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.osx-arm64) | >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 | 11.0.0 [Microsoft.AspNetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.osx-x64) | >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 | 11.0.0 [Microsoft.AspNetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-arm64) | >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 | 11.0.0 [Microsoft.AspNetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-x64) | >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 | 11.0.0 [Microsoft.AspNetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-x86) | >= 11.0.0-preview.6.26359.118, <= 11.0.0-rc.3.26522.148 | 11.0.0 ## Advisory FAQ ### How do I know if I am affected? Check the deployed runtime and application package versions against the affected ranges above. Self-contained applications include their own runtime; updating a machine-wide runtime does not replace it. ### How do I fix the issue? Install the applicable runtime or update each independently referenced package to the fixed version above. Restart applications. Rebuild and redeploy self-contained applications; updating a machine-wide runtime does not replace their embedded runtime. An SDK update alone does not update an application's standalone package references. ## Other Information ### Reporting Security Issues If you have found a potential security issue in a supported version of .NET, please report it to the Microsoft Security Response Center (MSRC) via the [MSRC Researcher Portal](https://msrc.microsoft.com/report/vulnerability/new). Further information can be found in the MSRC [Report an Issue FAQ](https://www.microsoft.com/msrc/faqs-report-an-issue). Security reports made through MSRC may qualify for the Microsoft .NET Bounty. Details of the Microsoft .NET Bounty Program including terms and conditions are at https://aka.ms/corebounty. ### Support You can ask questions about this issue on GitHub in the .NET GitHub organization. The main repos are located at https://github.com/dotnet/runtime. The Announcements repo (https://github.com/dotnet/Announcements) will contain this bulletin as an issue and will include a link to a discussion issue. You can ask questions in the linked discussion issue. ### Disclaimer The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply. ### External Links [CVE-2026-109481](https://www.cve.org/CVERecord?id=CVE-2026-109481) ### Acknowledgements - [Derek Haber](https://x.com/thecowboyhacker) with [Armadin](https://armadin.com/) - Anonymous - Artur Stetsko - s3zer0 - [Leonardo Souza](https://www.linkedin.com/in/capleonardo-souza) with [Delfia](https://delfia.tech/) - Attila.Cs(zerodaybugs.com) with https://zerodaybugs.com/ ### Revisions V1.0 (November 10, 2026): Advisory published. --- _Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_