Microsoft Security Advisory CVE-2026-50526 – .NET Tampering Vulnerability

Exploitation

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

CVSS

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

EPSS

• CVE-2026-50526: 0.22% estimated exploitation activity in the next 30 days; percentile 13.05 (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.

Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in .NET SDK (Microsoft.NET.Build.Containers). This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. A tampering vulnerability exists in the .NET SDK (.NET 8, .NET 9, and .NET 10) container image build process which could allow a local attacker to inject resources that could be incorporated into container images built by other users on the same machine. Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/TBD CVSS Details - Version: 3.1 - Severity: High - Score: 7.0 - Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness: CWE-59 (Improper Link Resolution Before File Access ('Link Following')) Affected Platforms - Platforms: All - Architectures: All <a name="affected-packages"</aAffected Packages The vulnerability affects any Microsoft .NET project if…

Published by the source

21 Jul 2026, 16:14 UTC

Last modified by the source

21 Jul 2026, 16:14 UTC

Source last checked

26 Oct 2026, 17:05 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-55jh-fwmh-39m4

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# Patch Next advisory brief: CVE-2026-50526

Advisory: Microsoft Security Advisory CVE-2026-50526 – .NET Tampering Vulnerability
IDs: CVE-2026-50526, GHSA-55jh-fwmh-39m4
Record: https://patchnext.com/advisories/cve-2026-50526 (revision 1, source checked 26 Oct 2026, 17:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: microsoft.net.build.containers 10.0.10, 9.0.18, 8.0.29. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet microsoft.net.build.containers: affected >= 10.0.0, <= 10.0.9; >= 9.0.0, <= 9.0.17; >= 8.0.0, <= 8.0.28; fixed in 8.0.29, 10.0.10, 9.0.18

## Suggested inspection (read-only)
- NuGet microsoft.net.build.containers: 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.net.build.containers.
- 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-55jh-fwmh-39m4 (GitHub-reviewed advisory GHSA-55jh-fwmh-39m4 lists affected ranges: NuGet microsoft.net.build.containers >=10.0.0 =9.0.0 =8.0.0 <=8.0.28)

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