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This library, ADAL for .NET, will no longer receive new feature improvements. Instead, use the new library MSAL for .NET.

Active Directory Authentication Library (ADAL) for .NET, Windows Store, .NET Core, Xamarin iOS and Xamarin Android

Conceptual documentation Code Samples Reference Docs Developer Guide API Reference Feedback

Update to MSAL.NET now!

MSAL.NET is the new authentication library to be used with the Microsoft identity platform

Building on top of ADAL, MSAL works with the new and Open ID Connect certified Azure AD V2 endpoint and the new social identity solution from Microsoft, Azure AD B2C.

ADAL.NET is in maintenance mode and no new features will be added to ADAL.NET anymore. All our ongoing efforts will be focused on improving the new MSAL.NET. MSAL’s documentation also contains a migration guide which simplifies upgrading from ADAL.NET, including how to migrate Xamarin.iOS apps using brokers.

ADAL.NET 2.x is no longer supported

ADAL.NET 2.x is no longer supported. ADAL.NET 3.x became generally available more than 3 years ago, superseding ADAL 2.x which was last released in August 2017 If you are still using 2.x, we recommend that you update directly to MSAL.NET


Active Directory Authentication Library for .NET (ADAL.NET) is an easy to use authentication library. You can use ADAL.NET to acquire security tokens to access protected Web APIs, for instance Microsoft Graph, or another Web APIs. ADAL.NET is available on various .NET Desktop/Mobile platforms to acquire a token for the signed-in user ( Windows desktop, UWP, Windows 8.1, Xamarin iOS and Xamarin Android). It can also be used in Web applications and Web APIs (ASP.NET, .NET Core, ASP.NET Core) that call other Web APIs in the name of a user, or without a user. ADAL.NET takes advantage of Windows Server Active Directory and Windows Azure Active Directory.

Release Location
Stable NuGet

Build status

dev adalV3/dev
Build status Build status


dev: Contains newest development of ADAL (v4+) adalV3/dev : Holds the v3 branch. Only security fixes will make it to v3.


Current version - latest one at
Minimum recommended version - 3.19.8

You can find the changes for each version in the change log.

Security Issue in Multiple Versions of ADAL .Net

A defect in ADAL .Net can result in an elevation of privilege in specific problem scenarios. The problem scenarios involve the On Behalf Of protocol flow and specific use cases of a ClientAssertion/ClientAssertionCertificate/ClientCredential and UserAssertion being passed to the AcquireToken* API. Multiple versions of the library are affected. Affected versions are listed below.

We have emailed owners of active applications that are using an impacted version of the library in the specific problem scenarios.

The latest stable version of the library does not have the defect. To avoid being impacted we strongly recommend you update to at least 2.28.1 for 2.x, 3.13.4 for 3.x, or the latest stable version. If you have questions about this issue, please email

Affected 2.x versions: 2.27.306291202, 2.26.305102204, 2.26.305100852, 2.25.305061457, 2.21.301221612, 2.20.301151232, 2.19.208020213, 2.18.206251556, 2.17.206230854, 2.16.204221202, 2.15.204151539, 2.14.201151115, 2.13.112191810, 2.12.111071459, 2.11.10918.1222, 2.10.10910.1511, 2.9.10826.1824, 2.8.10804.1442-rc, 2.7.10707.1513-rc, 2.6.2-alpha, 2.6.1-alpha, 2.5.1-alpha

Affected 3.x versions: 3.11.305310302-alpha, 3.10.305231913, 3.10.305161347, 3.10.305110106, 3.5.208051316-alpha, 3.5.208012240-alpha, 3.5.207081303-alpha, 3.4.206191646-alpha, 3.3.205061641-alpha, 3.2.204281119-alpha, 3.1.203031538-alpha, 3.0.110281957-alpha

Samples and Documentation

We provide a full suite of sample applications and ADAL documentation to help you get started with learning the Azure Identity system. Our Azure AD Developer Guide includes tutorials for native clients such as Windows, Windows Phone, iOS, OSX, Android, and Linux. We also provide full walkthroughs for authentication flows such as OAuth2, OpenID Connect, Graph API, and other awesome features.

Community Help and Support

We leverage Stack Overflow to work with the community on supporting Azure Active Directory and its SDKs, including this one! We highly recommend you ask your questions on Stack Overflow (we're all on there!) Also browser existing issues to see if someone has had your question before.

We recommend you use the "adal" tag so we can see it! Here is the latest Q&A on Stack Overflow for ADAL:

Submit Feedback

We'd like your thoughts on this library. Please complete this short survey.

Security Reporting

If you find a security issue with our libraries or services please report it to with as much detail as possible. Your submission may be eligible for a bounty through the Microsoft Bounty program. Please do not post security issues to GitHub Issues or any other public site. We will contact you shortly upon receiving the information. We encourage you to get notifications of when security incidents occur by visiting this page and subscribing to Security Advisory Alerts.


All code is licensed under the MIT license and we triage actively on GitHub. We enthusiastically welcome contributions and feedback. You can clone the repo and start contributing now, but check this document first.


The following are the primary sources of information for diagnosing issues:

  • Exceptions
  • Logs
  • Network traces

Also, note that correlation IDs are central to the diagnostics in the library. You can set your correlation IDs on a per request basis (by setting CorrelationId property on AuthenticationContext before calling an acquire token method) if you want to correlate an ADAL request with other operations in your code. If you don't set a correlations id, then ADAL will generate a random one which changes on each request. All log messages and network calls will be stamped with the correlation id.


This is obviously the first diagnostic. We try to provide helpful error messages. If you find one that is not helpful please file an issue and let us know. Please also provide the target platform of your application (e.g. Desktop, Windows Store, Windows Phone).


In order to configure logging, see the wiki page for implementation details.

Using brokers

See Leveraging brokers on Android and iOS

Network Traces

You can use various tools to capture the HTTP traffic that ADAL generates. This is most useful if you are familiar with the OAuth protocol or if you need to provide diagnostic information to Microsoft or other support channels.

Fiddler is the easiest HTTP tracing tool. In order to be useful it is necessary to configure fiddler to record unencrypted SSL traffic.

NOTE: Traces generated in this way may contain highly privileged information such as access tokens, usernames and passwords. If you are using production accounts, do not share these traces with 3rd parties. If you need to supply a trace to someone in order to get support, reproduce the issue with a temporary account with usernames and passwords that you don't mind sharing.


Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT License (the "License");

We Value and Adhere to the Microsoft Open Source Code of Conduct

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact with any additional questions or comments.