Use-After-Free in Microsoft.Native.Quic.MsQuic.Schannel (CVE-2026-85790)
Summary
Vulnerability in Microsoft.Native.Quic.MsQuic.Schannel (CVE-2026-85790). Confidential information can be exposed externally. Mitigation: upgrade to 2.6.2 or later.
Original description
The description as published by the source.
Executive summary
Microsoft 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.
Various vulnerabilities in MsQuic are addressed by an updated native-binary dependency update.
Announcement
Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/470
CVSS Details
-
Version: 3.1
-
Severity: Moderate
-
Score: 5.9
-
Vector:
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N -
Weakness: CWE-416 (Use After Free)
Affected Platforms
- Platforms: Windows
- Architectures: All
Affected Packages
The vulnerability affects Microsoft .NET projects that use an affected package version listed below.
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.Native.Quic.MsQuic.Schannel | >= 1.9.0, <= 2.6.1 | 2.6.2 |
Advisory FAQ
How do I know if I am affected?
If using a package listed in affected packages, you're exposed to the vulnerability.
How do I fix the issue?
- 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 up…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-85790 has been found in Microsoft.Native.Quic.MsQuic.Schannel.
Confidential information can be exposed externally. CVSS score: 5.9/10.
What to do: upgrade Microsoft.Native.Quic.MsQuic.Schannel to 2.6.2 or later.
If unsure, ask your IT team or search "Microsoft.Native.Quic.MsQuic.Schannel CVE-2026-85790" on the vendor's site.
CVE-2026-85790 (Microsoft.Native.Quic.MsQuic.Schannel) — CWE-416 / CVSS v3 5.9
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 2.6.2 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Use-after-free (CWE-416) exists in Microsoft.Native.Quic.MsQuic.Schannel.
Check the vendor advisory for the affected versions of Microsoft.Native.Quic.MsQuic.Schannel.
Severity: Medium (CVSS 5.9/10). Confidential information can be exposed externally.
Update to 2.6.2.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Microsoft.Native.Quic.MsQuic.Schannel' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'Microsoft.Native.Quic.MsQuic.Schannel' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
Microsoft.Native.Quic.MsQuic.Schannelを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Microsoft.Native.Quic.MsQuic.Schannel to 2.6.2ステージング環境で 2.6.2 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- package github.com
- patch secure@microsoft.com
- web github.com
- web github.com
- web github.com
- web github.com