Microsoft Security Advisory CVE-2026-96231 - .NET and Visual Studio Elevation of Privilege Vulnerability

Exploitation

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

CVSS

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

EPSS

• CVE-2026-96231: 0.41% estimated exploitation activity in the next 30 days; percentile 35.37 (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 Microsoft.NETCore.App.Runtime; System.Private.CoreLib. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. Unix named-mutex and shared-memory paths can be manipulated through insecure global directories, symlink races, and unsafe permission changes, allowing local attackers to truncate or overwrite files, widen directory permissions, or elevate privileges. Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/479 CVSS Details - Version: 3.1 - Severity: High - Score: 7.8 - Vector: CVSS:3.1/AV:L/AC:L/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: Linux, macOS - Architectures: All <a name="affected-packages"</aAffected Packages The vulnerability affects Microsoft…

Published by the source

13 Oct 2026, 20:44 UTC

Last modified by the source

13 Oct 2026, 21:00 UTC

Source last checked

26 Oct 2026, 17:05 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-2j93-m82w-73j2

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-2j93-m82w-73j2

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# Patch Next advisory brief: CVE-2026-96231

Advisory: Microsoft Security Advisory CVE-2026-96231 - .NET and Visual Studio Elevation of Privilege Vulnerability
IDs: CVE-2026-96231, GHSA-2j93-m82w-73j2
Record: https://patchnext.com/advisories/cve-2026-96231 (revision 2, 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 7.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: microsoft.netcore.app.runtime.linux-musl-x64 11.0.0-rc.2, 10.0.13, 9.0.21, 8.0.32; microsoft.netcore.app.runtime.linux-arm64 11.0.0-rc.2, 10.0.13, 9.0.21, 8.0.32; microsoft.netcore.app.runtime.linux-arm 11.0.0-rc.2, 10.0.13, 9.0.21, 8.0.32; microsoft.netcore.app.runtime.osx-x64 11.0.0-rc.2, 10.0.13, 9.0.21, 8.0.32; microsoft.netcore.app.runtime.linux-x64 11.0.0-rc.2, 10.0.13, 9.0.21, 8.0.32; microsoft.netcore.app.runtime.osx-arm64 11.0.0-rc.2, 10.0.13, 9.0.21, 8.0.32; microsoft.netcore.app.runtime.linux-musl-arm 11.0.0-rc.2, 10.0.13, 9.0.21, 8.0.32; microsoft.netcore.app.runtime.linux-musl-arm64 11.0.0-rc.2, 10.0.13, 9.0.21, 8.0.32. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet microsoft.netcore.app.runtime.linux-musl-x64: affected >= 8.0.0, <= 8.0.31; >= 10.0.0, <= 10.0.12; >= 9.0.0, <= 9.0.20; >= 11.0.0-preview.1, <= 11.0.0-rc.1; fixed in 11.0.0-rc.2, 10.0.13, 8.0.32, 9.0.21
- NuGet microsoft.netcore.app.runtime.linux-arm64: affected >= 8.0.0, <= 8.0.31; >= 10.0.0, <= 10.0.12; >= 9.0.0, <= 9.0.20; >= 11.0.0-preview.1, <= 11.0.0-rc.1; fixed in 11.0.0-rc.2, 10.0.13, 8.0.32, 9.0.21
- NuGet microsoft.netcore.app.runtime.linux-arm: affected >= 8.0.0, <= 8.0.31; >= 10.0.0, <= 10.0.12; >= 9.0.0, <= 9.0.20; >= 11.0.0-preview.1, <= 11.0.0-rc.1; fixed in 11.0.0-rc.2, 10.0.13, 8.0.32, 9.0.21
- NuGet microsoft.netcore.app.runtime.osx-x64: affected >= 8.0.0, <= 8.0.31; >= 10.0.0, <= 10.0.12; >= 9.0.0, <= 9.0.20; >= 11.0.0-preview.1, <= 11.0.0-rc.1; fixed in 11.0.0-rc.2, 10.0.13, 8.0.32, 9.0.21
- NuGet microsoft.netcore.app.runtime.linux-x64: affected >= 8.0.0, <= 8.0.31; >= 10.0.0, <= 10.0.12; >= 9.0.0, <= 9.0.20; >= 11.0.0-preview.1, <= 11.0.0-rc.1; fixed in 11.0.0-rc.2, 10.0.13, 8.0.32, 9.0.21
- NuGet microsoft.netcore.app.runtime.osx-arm64: affected >= 8.0.0, <= 8.0.31; >= 10.0.0, <= 10.0.12; >= 9.0.0, <= 9.0.20; >= 11.0.0-preview.1, <= 11.0.0-rc.1; fixed in 11.0.0-rc.2, 10.0.13, 8.0.32, 9.0.21
- NuGet microsoft.netcore.app.runtime.linux-musl-arm: affected >= 8.0.0, <= 8.0.31; >= 10.0.0, <= 10.0.12; >= 9.0.0, <= 9.0.20; >= 11.0.0-preview.1, <= 11.0.0-rc.1; fixed in 11.0.0-rc.2, 10.0.13, 8.0.32, 9.0.21
- NuGet microsoft.netcore.app.runtime.linux-musl-arm64: affected >= 8.0.0, <= 8.0.31; >= 10.0.0, <= 10.0.12; >= 9.0.0, <= 9.0.20; >= 11.0.0-preview.1, <= 11.0.0-rc.1; fixed in 11.0.0-rc.2, 10.0.13, 8.0.32, 9.0.21

## Suggested inspection (read-only)
- NuGet microsoft.netcore.app.runtime.linux-musl-x64: check the installed version with your package manager.
- NuGet microsoft.netcore.app.runtime.linux-arm64: check the installed version with your package manager.
- NuGet microsoft.netcore.app.runtime.linux-arm: check the installed version with your package manager.
- NuGet microsoft.netcore.app.runtime.osx-x64: check the installed version with your package manager.
- NuGet microsoft.netcore.app.runtime.linux-x64: check the installed version with your package manager.
- NuGet microsoft.netcore.app.runtime.osx-arm64: check the installed version with your package manager.
- NuGet microsoft.netcore.app.runtime.linux-musl-arm: check the installed version with your package manager.
- NuGet microsoft.netcore.app.runtime.linux-musl-arm64: 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.netcore.app.runtime.linux-musl-x64, microsoft.netcore.app.runtime.linux-arm64, microsoft.netcore.app.runtime.linux-arm, microsoft.netcore.app.runtime.osx-x64, microsoft.netcore.app.runtime.linux-x64, microsoft.netcore.app.runtime.osx-arm64, microsoft.netcore.app.runtime.linux-musl-arm, microsoft.netcore.app.runtime.linux-musl-arm64.
- 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://osv.dev/vulnerability/GHSA-2j93-m82w-73j2 (OSV record GHSA-2j93-m82w-73j2 lists affected ranges: NuGet microsoft.netcore.app.runtime.linux-arm >=8.0.0 =10.0.0 =9.0.0 =11.0.0-preview.1 =8.0.0 =10.0.0 =9.0.0 =11.0.0-preview.1 =8.0.0 =10.0.0 =9.0.0…)
- Verified: https://github.com/advisories/GHSA-2j93-m82w-73j2 (GitHub-reviewed advisory GHSA-2j93-m82w-73j2 lists affected ranges: NuGet microsoft.netcore.app.runtime.linux-arm >=8.0.0 =10.0.0 =9.0.0 =11.0.0-preview.1 =8.0.0 =10.0.0 =9.0.0 =11.0.0-preview.1 =8.0.0 =10.0.0 =9.0.0 =11.0.0-preview.1 <=11.0.0-rc.1; NuGet…)

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