Improper Certificate Validation in Microsoft .NET Framework components

Exploitation

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

CVSS

5.5 · CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

EPSS

• CVE-2018-8356: 0.75% estimated exploitation activity in the next 30 days; percentile 54.94 (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.

A security feature bypass vulnerability exists when Microsoft .NET Framework components do not correctly validate certificates, aka ".NET Framework Security Feature Bypass Vulnerability." This affects .NET Framework 4.7.2, Microsoft .NET Framework 3.0, Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2, ASP.NET Core 1.1, Microsoft .NET Framework 4.5.2, ASP.NET Core 2.0, ASP.NET Core 1.0, .NET Core 1.1, Microsoft .NET Framework 3.5, Microsoft .NET Framework 3.5.1, Microsoft .NET Framework 4.6/4.6.1/4.6.2, .NET Core 1.0, .NET Core 2.0, Microsoft .NET Framework 4.6, Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.1/4.7.2, Microsoft .NET Framework 4.7.2.

Published by the source

14 May 2022, 03:00 UTC

Last modified by the source

29 Jan 2023, 05:02 UTC

Source last checked

26 Oct 2026, 16:58 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-p9wx-v264-q34p

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# Patch Next advisory brief: CVE-2018-8356

Advisory: Improper Certificate Validation in Microsoft .NET Framework components
IDs: CVE-2018-8356, GHSA-p9wx-v264-q34p
Record: https://patchnext.com/advisories/cve-2018-8356 (revision 1, source checked 26 Oct 2026, 16:58 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: system.servicemodel.duplex 4.5.3, 4.4.4, 4.3.3, 4.0.4; system.servicemodel.primitives 4.5.3, 4.4.4, 4.3.3, 4.1.3; system.servicemodel.http 4.5.3, 4.4.4, 4.3.3, 4.1.3; system.servicemodel.security 4.5.3, 4.4.4, 4.3.3, 4.0.4; system.servicemodel.nettcp 4.5.3, 4.4.4, 4.3.3, 4.1.3; system.private.servicemodel 4.5.3, 4.4.4, 4.3.3, 4.1.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet system.servicemodel.duplex: affected >= 4.3.0, < 4.3.3; >= 4.4.0, < 4.4.4; >= 4.5.0, < 4.5.3; >= 4.0.0, <= 4.0.2; fixed in 4.4.4, 4.5.3, 4.3.3, 4.0.4
- NuGet system.servicemodel.primitives: affected >= 4.3.0, < 4.3.3; >= 4.4.0, < 4.4.4; >= 4.5.0, < 4.5.3; >= 4.0.0, < 4.1.3; fixed in 4.1.3, 4.4.4, 4.5.3, 4.3.3
- NuGet system.servicemodel.http: affected >= 4.3.0, < 4.3.3; >= 4.4.0, < 4.4.4; >= 4.5.0, < 4.5.3; >= 4.0.0, < 4.1.3; fixed in 4.1.3, 4.4.4, 4.5.3, 4.3.3
- NuGet system.servicemodel.security: affected >= 4.3.0, < 4.3.3; >= 4.4.0, < 4.4.4; >= 4.5.0, < 4.5.3; >= 4.0.0, <= 4.0.2; fixed in 4.4.4, 4.5.3, 4.3.3, 4.0.4
- NuGet system.servicemodel.nettcp: affected >= 4.3.0, < 4.3.3; >= 4.4.0, < 4.4.4; >= 4.5.0, < 4.5.3; >= 4.0.0, < 4.1.3; fixed in 4.1.3, 4.4.4, 4.5.3, 4.3.3
- NuGet system.private.servicemodel: affected >= 4.0.0, < 4.1.3; >= 4.3.0, < 4.3.3; >= 4.4.0, < 4.4.4; >= 4.5.0, < 4.5.3; fixed in 4.1.3, 4.4.4, 4.5.3, 4.3.3

## Suggested inspection (read-only)
- NuGet system.servicemodel.duplex: check the installed version with your package manager.
- NuGet system.servicemodel.primitives: check the installed version with your package manager.
- NuGet system.servicemodel.http: check the installed version with your package manager.
- NuGet system.servicemodel.security: check the installed version with your package manager.
- NuGet system.servicemodel.nettcp: check the installed version with your package manager.
- NuGet system.private.servicemodel: 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 system.servicemodel.duplex, system.servicemodel.primitives, system.servicemodel.http, system.servicemodel.security, system.servicemodel.nettcp, system.private.servicemodel.
- 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-p9wx-v264-q34p (GitHub-reviewed advisory GHSA-p9wx-v264-q34p lists affected ranges: NuGet system.private.servicemodel >=4.0.0 =4.3.0 =4.4.0 =4.5.0 =4.3.0 =4.4.0 =4.5.0 =4.0.0 =4.3.0 =4.4.0 =4.5.0 =4.0.0 =4.3.0 =4.4.0 =4.5.0 =4.0.0 <4.1.3; NuGet system.servicemodel.primitives…)

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