Microsoft Security Advisory CVE-2025-24070: .NET Elevation of Privilege Vulnerability

[rbhanda]

Microsoft Security Advisory CVE-2025-24070: .NET Elevation of Privilege Vulnerability

Executive summary

Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core 9.0 , ASP.NET Core 8.0, and ASP.NET Core 2.3. This advisory also provides guidance on what developers can do to update their applications to address this vulnerability.

A vulnerability exists in ASP.NET Core applications calling RefreshSignInAsync with an improperly authenticated user parameter that could allow an attacker to sign into another user's account, resulting in Elevation of Privilege.

Announcement

Announcement for this issue can be found at dotnet/announcements#348

Mitigation factors

Microsoft has not identified any mitigating factors for this vulnerability.

Affected software

• Any ASP.NET Core 9.0 application running on ASP.NET Core 9.0.2 or earlier.
• Any ASP.NET Core application running on ASP.NET Core 8.0.13 or earlier.
• Any ASP.NET Core 2.x application consuming the package Microsoft.AspNetCore.Identity version 2.3.0 or earlier.

Affected Packages

The vulnerability affects any Microsoft .NET Core project if it uses any of affected packages versions listed below

Package name	Affected version	Patched version
Microsoft.AspNetCore.Identity	2.3.0	2.3.1

ASP.NET Core 9

Package name	Affected version	Patched version
Microsoft.AspNetCore.App.Runtime.linux-arm	>= 9.0.0, <= 9.0.2	9.0.3
Microsoft.AspNetCore.App.Runtime.linux-arm64	>= 9.0.0, <= 9.0.2	9.0.3
Microsoft.AspNetCore.App.Runtime.linux-musl-arm	>= 9.0.0, <= 9.0.2	9.0.3
Microsoft.AspNetCore.App.Runtime.linux-musl-arm64	>= 9.0.0, <= 9.0.2	9.0.3
Microsoft.AspNetCore.App.Runtime.linux-musl-x64	>= 9.0.0, <= 9.0.2	9.0.3
Microsoft.AspNetCore.App.Runtime.linux-x64	>= 9.0.0, <= 9.0.2	9.0.3
Microsoft.AspNetCore.App.Runtime.osx-arm64	>= 9.0.0, <= 9.0.2	9.0.3
Microsoft.AspNetCore.App.Runtime.osx-x64	>= 9.0.0, <= 9.0.2	9.0.3
Microsoft.AspNetCore.App.Runtime.win-arm	>= 9.0.0, <= 9.0.2	9.0.3
Microsoft.AspNetCore.App.Runtime.win-arm64	>= 9.0.0, <= 9.0.2	9.0.3
Microsoft.AspNetCore.App.Runtime.win-x64	>= 9.0.0, <= 9.0.2	9.0.3
Microsoft.AspNetCore.App.Runtime.win-x86	>= 9.0.0, <= 9.0.2	9.0.3

ASP.NET Core 8

Package name	Affected version	Patched version
Microsoft.AspNetCore.App.Runtime.linux-arm	>= 8.0.0, <= 8.0.13	8.0.14
Microsoft.AspNetCore.App.Runtime.linux-arm64	>= 8.0.0, <= 8.0.13	8.0.14
Microsoft.AspNetCore.App.Runtime.linux-musl-arm	>= 8.0.0, <= 8.0.13	8.0.14
Microsoft.AspNetCore.App.Runtime.linux-musl-arm64	>= 8.0.0, <= 8.0.13	8.0.14
Microsoft.AspNetCore.App.Runtime.linux-musl-x64	>= 8.0.0, <= 8.0.13	8.0.14
Microsoft.AspNetCore.App.Runtime.linux-x64	>= 8.0.0, <= 8.0.13	8.0.14
Microsoft.AspNetCore.App.Runtime.osx-arm64	>= 8.0.0, <= 8.0.13	8.0.14
Microsoft.AspNetCore.App.Runtime.osx-x64	>= 8.0.0, <= 8.0.13	8.0.14
Microsoft.AspNetCore.App.Runtime.win-arm	>= 8.0.0, <= 8.0.13	8.0.14
Microsoft.AspNetCore.App.Runtime.win-arm64	>= 8.0.0, <= 8.0.13	8.0.14
Microsoft.AspNetCore.App.Runtime.win-x64	>= 8.0.0, <= 8.0.13	8.0.14
Microsoft.AspNetCore.App.Runtime.win-x86	>= 8.0.0, <= 8.0.13	8.0.14

Advisory FAQ

How do I know if I am affected?

If you have a runtime or SDK with a version listed, or an affected package listed in affected software or affected packages, you're exposed to the vulnerability.

How do I fix the issue?

1. To fix the issue please install the latest version of .NET 9.0. If you have installed one or more .NET SDKs through Visual Studio, Visual Studio will prompt you to update Visual Studio, which will also update your .NET SDKs.
2. If your application references the vulnerable package, update the package reference to the patched version.

• You can list the versions you have installed by running the dotnet --info command. You will see output like the following;

.NET SDK:
 Version:           9.0.100
 Commit:            59db016f11
 Workload version:  9.0.100-manifests.3068a692
 MSBuild version:   17.12.7+5b8665660

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  15.2
 OS Platform: Darwin
 RID:         osx-arm64
 Base Path:   /usr/local/share/dotnet/sdk/9.0.100/

.NET workloads installed:
There are no installed workloads to display.
Configured to use loose manifests when installing new manifests.

Host:
  Version:      9.0.0
  Architecture: arm64
  Commit:       9d5a6a9aa4

.NET SDKs installed:
  9.0.100 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 9.0.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 9.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
  x64   [/usr/local/share/dotnet]
    registered at [/etc/dotnet/install_location_x64]

Environment variables:
  Not set

global.json file:
  Not found

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download

• If you're using .NET 9.0, you should download and install .NET 9.0.3 Runtime or .NET 9.0.103 SDK (for Visual Studio 2022 v17.12 latest Preview) from https://dotnet.microsoft.com/download/dotnet-core/9.0.

Once you have installed the updated runtime or SDK, restart your apps for the update to take effect.

Additionally, if you've deployed self-contained applications targeting any of the impacted versions, these applications are also vulnerable and must be recompiled and redeployed.

Other Information

Reporting Security Issues

If you have found a potential security issue in .NET 8.0 or .NET 9.0, please email details to secure@microsoft.com. Reports may qualify for the Microsoft .NET Core & .NET 5 Bounty. Details of the Microsoft .NET Bounty Program including terms and conditions are at https://aka.ms/corebounty.

Support

You can ask questions about this issue on GitHub in the .NET GitHub organization. The main repos are located at https://github.com/dotnet/aspnetcore. The Announcements repo (https://github.com/dotnet/Announcements) will contain this bulletin as an issue and will include a link to a discussion issue. You can ask questions in the linked discussion issue.

Disclaimer

The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.

External Links

Acknowledgement

Zahid TOKAT

CVE-2025-24070

Revisions

V1.0 (March 11, 2025): Advisory published.

Version 1.0

Last Updated 2025-03-11

[Sebazzz]

I like to have some more information on the nature of the vulnerability. At first I thought “Wow, a security issue in ASP.NET Core identity which is used in like all the applications I’m involved in”, but looking at the source of RefreshSignin it appears that the only vector that is arbitrary, is attempting to refresh with a different user that is currently signed in. The claims principal itself is protected by the encrypted cookie or token, and if those encryption keys are leaked you have a whole other host of issues.

Must also note that you must either use the default ASP.NET Core Identity UI (which calls RefreshSignin) or call RefreshSignin yourself. There appears to be no ASP.NET Core code other than the built-in identity UI calling the vulnerable code.

edit: Seems to be PR #60881 - commit d42bdf6 - exactly what I thought. Honestly, if you were calling RefreshSignin with the wrong user you are probably already accepting user input where it isn't needed.