Remote Denial of Service Vulnerability in Microsoft.Native.Quic.MsQuic.Schannel

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2023-38171: 71.05% estimated exploitation activity in the next 30 days; percentile 99.41 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact The MsQuic server application or process will crash, resulting in a denial of service. Patches The following patch was made: - Don't Allow Version Negotiation Packets for Server Connections - https://github.com/microsoft/msquic/commit/3226cff07d22662f16fc98d605656860e64cd343 Workarounds Beyond upgrading to the patched versions, there is no other workaround. You must upgrade or disable MsQuic functionality.

Published by the source

10 Oct 2023, 21:23 UTC

Last modified by the source

3 Jun 2024, 18:35 UTC

Source last checked

26 Oct 2026, 17:00 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-xh5m-8qqp-c5x7

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# Patch Next advisory brief: CVE-2023-38171

Advisory: Remote Denial of Service Vulnerability in Microsoft.Native.Quic.MsQuic.Schannel
IDs: CVE-2023-38171, GHSA-xh5m-8qqp-c5x7
Record: https://patchnext.com/advisories/cve-2023-38171 (revision 1, source checked 26 Oct 2026, 17:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: microsoft.native.quic.msquic.schannel 2.2.3; microsoft.native.quic.msquic.openssl 2.2.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet microsoft.native.quic.msquic.schannel: affected < 2.2.3; fixed in 2.2.3
- NuGet microsoft.native.quic.msquic.openssl: affected < 2.2.3; fixed in 2.2.3

## Suggested inspection (read-only)
- NuGet microsoft.native.quic.msquic.schannel: check the installed version with your package manager.
- NuGet microsoft.native.quic.msquic.openssl: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on microsoft.native.quic.msquic.schannel, microsoft.native.quic.msquic.openssl.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-xh5m-8qqp-c5x7 (GitHub-reviewed advisory GHSA-xh5m-8qqp-c5x7 lists affected ranges: NuGet microsoft.native.quic.msquic.schannel >=0 =0 <2.2.3)

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