{"id":"CVE-2026-85790","kind":"vulnerability","aliases":["CVE-2026-85790","GHSA-2mxg-prvg-9jfg"],"related":[],"title":"Microsoft Security Advisory CVE-2026-85790 - .NET Information Disclosure Vulnerability","description":"## Executive summary\n\nMicrosoft is releasing this security advisory to provide information about a vulnerability in Microsoft.Native.Quic.MsQuic.Schannel. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.\n\nVarious vulnerabilities in MsQuic are addressed by an updated native-binary dependency update.\n\n## Announcement\n\nAnnouncement for this issue can be found at https://github.com/dotnet/announcements/issues/470\n\n## CVSS Details\n\n- **Version:** 3.1\n- **Severity:** Moderate\n- **Score:** 5.9\n- **Vector:** `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N`\n\n- **Weakness:** CWE-416 (Use After Free)\n## Affected Platforms\n\n- **Platforms:** Windows\n- **Architectures:** All\n\n## <a name=\"affected-packages\"></a>Affected Packages\n\nThe vulnerability affects Microsoft .NET projects that use an affected package version listed below.\n\nPackage name | Affected version | Patched version\n------------ | ---------------- | ---------------\n[Microsoft.Native.Quic.MsQuic.Schannel](https://www.nuget.org/packages/Microsoft.Native.Quic.MsQuic.Schannel) | >= 1.9.0, < 2.5.12 | 2.5.12\n[Microsoft.Native.Quic.MsQuic.Schannel](https://www.nuget.org/packages/Microsoft.Native.Quic.MsQuic.Schannel) | >= 2.6.0, < 2.6.3 | 2.6.3\n\n## Advisory FAQ\n\n### <a name=\"how-affected\"></a>How do I know if I am affected?\n\nIf using a package listed in [affected packages](#affected-packages), you're exposed to the vulnerability.\n\n### <a name=\"how-fix\"></a>How do I fix the issue?\n\n1. To fix the issue please install the latest version of .NET. If you have installed one or more .NET SDKs through Visual Studio, Visual Studio will prompt you to update Visual Studio, which will also update your .NET SDKs.\n2. If your application references the vulnerable package, update the package reference to the patched version. You can list the versions you have installed by running the `dotnet --info` command.\n\nOnce you have installed the updated runtime or SDK, restart your apps for the update to take effect.\n\nAdditionally, if you've deployed [self-contained applications](https://docs.microsoft.com/dotnet/core/deploying/#self-contained-deployments-scd) targeting any of the impacted versions, these applications are also vulnerable and must be recompiled and redeployed.\n\n## Other Information\n\n### Reporting Security Issues\n\nIf 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).\n\nSecurity 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.\n\n### Support\n\nYou 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.\n\n### Disclaimer\n\nThe 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.\n\n### External Links\n\n[CVE-2026-85790](https://www.cve.org/CVERecord?id=CVE-2026-85790)\n\n### Acknowledgements\n\n- reinusKR","summary":"A use-after-free flaw (CWE-416) in the NuGet package Microsoft.Native.Quic.MsQuic.Schannel, which ships MsQuic for .NET on Windows, has a CVSS 3.1 score of 5.9 with high confidentiality impact. The advisory text says an attacker may read information from memory, with no authentication needed, but the sources do not describe the exact trigger.","severity":"medium","cvss":5.900000095367432,"epss":0.006899999920278788,"exploited":false,"exploited_at":null,"products":[{"name":"Microsoft.Native.Quic.MsQuic.Schannel","fixed":["2.5.12"],"affected":">= 1.9.0, < 2.5.12","ecosystem":"nuget"},{"name":"Microsoft.Native.Quic.MsQuic.Schannel","fixed":["2.6.3"],"affected":">= 2.6.0, < 2.6.3","ecosystem":"nuget"},{"name":"microsoft windows 11 23h2","fixed":["10.0.22631.7652"],"affected":"< 10.0.22631.7652","ecosystem":"vendor"},{"name":"microsoft windows 11 24h2","fixed":["10.0.26100.9711"],"affected":"< 10.0.26100.9711","ecosystem":"vendor"},{"name":"microsoft windows 11 25h2","fixed":["10.0.26200.9711"],"affected":"< 10.0.26200.9711","ecosystem":"vendor"},{"name":"microsoft windows 11 26h1","fixed":["10.0.28000.3231"],"affected":"< 10.0.28000.3231","ecosystem":"vendor"},{"name":"microsoft windows 11 26h2","fixed":["10.0.26300.9711"],"affected":"< 10.0.26300.9711","ecosystem":"vendor"},{"name":"microsoft windows server 2022","fixed":["10.0.20348.5761"],"affected":"< 10.0.20348.5761","ecosystem":"vendor"},{"name":"microsoft windows server 2025","fixed":["10.0.26100.33650"],"affected":"< 10.0.26100.33650","ecosystem":"vendor"},{"name":"microsoft native.quic.msquic.schannel","fixed":["2.6.2"],"affected":"< 2.6.2","ecosystem":"vendor"},{"name":"microsoft visual studio 2022","fixed":["17.14.42"],"affected":">= 17.14.0, < 17.14.42","ecosystem":"vendor"},{"name":"microsoft visual studio 2026","fixed":["18.10.4"],"affected":">= 18.10.0, < 18.10.4","ecosystem":"vendor"}],"ecosystems":["nuget","vendor"],"tags":["cwe-416","dotnet","nuget","package","quic","self-contained-apps","windows"],"not_affected_if":["linux-only","macos-only","package-version-outside-affected-ranges"],"how_to_check":"Run dotnet --info and check whether the .NET SDK or runtime is older than the patched release.\nSearch project files and lockfiles for Microsoft.Native.Quic.MsQuic.Schannel and compare the version to the affected ranges (>= 1.9.0 < 2.5.12, or >= 2.6.0 < 2.6.3).\nFor self-contained apps, check the version they were published with, since they bundle their own copy.","fix":"Update the package reference to 2.5.12 (for the 2.5 line) or 2.6.3 (for the 2.6 line), then rebuild.\nInstall the latest .NET release, restart apps, and recompile and redeploy self-contained apps built against an affected version.","status":"open","published_at":"2026-10-13T19:21:02+00:00","first_seen_at":"2026-10-23T19:11:32+00:00","triaged_at":"2026-10-23T19:58:00+00:00","updated_at":"2026-10-23T23:44:52+00:00","category":"package","confidence":0.75,"triage":{"at":"2026-10-23T19:58:00Z","model":"claude-haiku-5-5","output":{"fix":"Update the package reference to 2.5.12 (for the 2.5 line) or 2.6.3 (for the 2.6 line), then rebuild.\nInstall the latest .NET release, restart apps, and recompile and redeploy self-contained apps built against an affected version.","summary":"A use-after-free flaw (CWE-416) in the NuGet package Microsoft.Native.Quic.MsQuic.Schannel, which ships MsQuic for .NET on Windows, has a CVSS 3.1 score of 5.9 with high confidentiality impact. The advisory text says an attacker may read information from memory, with no authentication needed, but the sources do not describe the exact trigger.","category":"package","who_cares":["dotnet","windows","nuget","quic","self-contained-apps"],"confidence":0.75,"analyst_note":"Check the Microsoft announcement at https://github.com/dotnet/announcements/issues/470 for the specific trigger and whether non-Windows builds are affected; sources say only Windows.","how_to_check":"Run dotnet --info and check whether the .NET SDK or runtime is older than the patched release.\nSearch project files and lockfiles for Microsoft.Native.Quic.MsQuic.Schannel and compare the version to the affected ranges (>= 1.9.0 < 2.5.12, or >= 2.6.0 < 2.6.3).\nFor self-contained apps, check the version they were published with, since they bundle their own copy.","needs_analyst":true,"not_affected_if":["linux-only","macos-only","package-version-outside-affected-ranges"],"severity_if_unknown":"medium"},"cost_usd":0.000636,"input_tokens":3573,"output_tokens":558,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-2026':5A,12A,20A,645C '-416':63B,80B,210C '-85790':6A,13A,21A,646C '/av':199C '/corebounty.':485C '/dotnet/announcements)':515C '/dotnet/announcements/issues/470':187C '/dotnet/core/deploying/#self-contained-deployments-scd)':388C '/dotnet/runtime.':509C '/msrc/faqs-report-an-issue).':457C '/packages/microsoft.native.quic.msquic.schannel)':245C,252C '/report/vulnerability/new).':442C '1':289C '1.9.0':246C '11':26A,30A,34A,38A,42A '2':329C '2.5.12':247C,248C '2.6.0':253C '2.6.3':254C,255C '2022':47A,57A '2025':51A '2026':61A '23h2':27A '24h2':31A '25h2':35A '26h1':39A '26h2':43A '2mxg':16A '3.1':96B,191C,198C '5.9':99B,195C '9jfg':18A 'addit':377C 'address':167C 'advis':612C 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human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}