What's Changed

• Security fixes and general reliability improvements.

Full Changelog: 4.16.0...4.16.1

What's Changed

• Add 4.15.0 release notes by Iarek Kovtunenko (@iarekk) in #4050
• Post-release 4.15.0: mark APIs shipped and bump version by Iarek Kovtunenko (@iarekk) in #4060
• Add Sidecar 1.1.2 changelog by Tanuj Sood (@soodt) in #4070
• Fix FIC telemetry enrichment during credential warm-up and assertion cache hits by Neha Bhargava (@neha-bhargava) in #4072
• Update agentic docs to cover current behavior by Avery-Dunn in #4077
• Bump the notsecurity group with 4 updates by Dependabot (@dependabot)[bot] in #4074

Full Changelog: 4.15.0...4.16.0

Federated credentials and proof of possession

• Federated credential token exchange derives cloud-specific audience and scope metadata from the authority host, with explicit overrides still supported. #3994
• The Entra Sidecar /Validate endpoint accepts Signed HTTP Request proof-of-possession tokens for app-only client-credential flows. #4008
• Credential Guard key attestation is available through the optional Microsoft.Identity.Web.KeyAttestation package and AddMicrosoftIdentityWebKeyAttestation() registration. #4004

Authentication and token acquisition

• EasyAuth app-token acquisition returns an app-only authentication result produced through client credentials. #4015
• Graph v4 credentials are attached only to destinations matching the configured absolute HTTPS origin; custom Graph proxy base URLs remain supported. #4012

Authorization and request validation

• OWIN web APIs require a non-empty recognized scope or role unless ACL-based authorization is explicitly enabled. #4006 #4009
• Explicitly configured missing scope or app-permission requirements now fail authorization. #4010
• Local redirect paths containing control characters are rejected. #4028

Entra Sidecar reliability and validation

• Invalid selected AgentUserId values return HTTP 400. #4011
• Automatic forwarded-header processing is rejected outside Development when ForwardedHeaders_Enabled=true. #4018
• Non-local Host headers are rejected outside Development except on /healthz. #4023
• Windows containers use ContainerUser, and ACL authorization defaults are correctly applied to named bearer options. #4042

Dependency updates

• Microsoft.Identity.Client and Microsoft.Identity.Client.KeyAttestation: 4.87.0 -> 4.90.0. #4003 #3994 #4052
• Microsoft.Identity.Abstractions: 12.6.0 -> 12.7.0. #4020 #3994

Full changelog: 4.14.2...4.15.0

What's Changed

• Security fixes and general reliability improvements.

Full Changelog: 3.15.1...3.16.0

Dependencies updates

• Bump the Microsoft.IdentityModel.* (Wilson) version to 8.22.0. See #3986.
• Fix the net8.0 crypto floor to use the patched System.Security.Cryptography.Xml 8.0.4 (and its System.Security.Cryptography.Pkcs 8.0.1 dependency) instead of over-bumping to the 9.0.18 servicing line (CVE-2026-47302, -47304, -50525, -50648). net9.0 (9.0.18) and net10.0 (10.0.10) are unchanged. See #3989.

New features

• Add MicrosoftIdentityOptions.PartitionAppTokenCacheByAudience to partition the app token cache by resource/audience. See #3979.
• Expose MSAL's background token-refresh callback through Id.Web via TokenAcquisitionExtensionOptions.OnBackgroundTokenRefreshCompleted. See #3973.
• Add MicrosoftIdentityOptions.UseFastUnboundedCache; stop short-circuiting the in-memory token cache serialization provider. See #3970.
• OIDC FIC (Microsoft.Identity.Web.OidcFIC) now supports mTLS token binding. See #3851.

Bug fixes

• Token binding: the CCA cache key now distinguishes a bound credential (UseBoundCredential = true) from its unbound equivalent; the certificate-error retry path invalidates the cache entry for the actual request mode (bearer vs mTLS PoP).
• Forward the OpenTelemetry tags enricher onto the inner FIC client-assertion leg. See #3968.

Dependencies updates

• Microsoft.Identity.Client → 4.87.0 (#3975)
• Microsoft.Identity.Abstractions → 12.6.0 (#3976)
• System.Security.Cryptography.Xml / System.Security.Cryptography.Pkcs → patched (CVE-2026-47302, -47304, -50525, -50648) (#3964)
• notsecurity group: 1 update (#3965)

Full changelog: 4.13.2...4.14.0

What's Changed

• Apply reserved-header handling on the request-clone path and cover all X-MS-TOKEN- headers by Ignacio Inglese (@iNinja) in #3915
• Restore independent PR pipeline + pool-aware MI identity + net462/472 unit tests by Iarek Kovtunenko (@iarekk) in #3935
• Post-release 4.13.0: changelog and public API shipped move by Neha Bhargava (@neha-bhargava) in #3937
• Remove redundant 'Run unit tests' GitHub Action by Iarek Kovtunenko (@iarekk) in #3939
• Apply consistent redirect-URI validation on AccountController.SignIn by Ignacio Inglese (@iNinja) in #3940
• Fix duplicate logging of MsalUiRequiredException (in-repo copy of #3910) by Iarek Kovtunenko (@iarekk) in #3941
• Use MSAL's recent UserFIC API for agentic flows by Avery-Dunn in #3842
• Restore CustomizeHttpRequestMessage to run after the authorization header by Neha Bhargava (@neha-bhargava) in #3943
• Bump Microsoft.IdentityModel.Tokens.Saml from 5.7.0 to 8.19.1 by Dependabot (@dependabot)[bot] in #3909
• Revert #3909: keep OWIN Saml/WsFederation on 5.7.0 by Iarek Kovtunenko (@iarekk) in #3944
• Bump Microsoft.Identity.Abstractions from 12.4.0 to 12.5.0 by Neha Bhargava (@neha-bhargava) in #3947
• Add OnBeforeAuthHeaderCreation / OnAfterAuthHeaderCreation hooks to DownstreamApi by Neha Bhargava (@neha-bhargava) in #3942
• Update IdentityModelV5Version and SamlPackageVersion to 5.7.1 in proj… by Travis Walker (@trwalke) in #3950
• Rename retired MSALMSIV2 agent pool to MISEManagedIdentity by Gladwin Johnson VR (@gladjohn) with @Copilot in #3949
• Improve IDW10109 error handling for credential loading failures by Avery-Dunn in #3946
• Bump MSAL dependencies to 4.86.1 in central props by Gladwin Johnson VR (@gladjohn) with @Copilot in #3953
• Bump the notsecurity group with 3 updates by Dependabot (@dependabot)[bot] in #3954

Full Changelog: 4.13.0...4.13.2

What's Changed

• Categorize managed-identity E2E tests and exclude them from the PR build by Iarek Kovtunenko (@iarekk) in #3923
• Add more tests for TokenAcquisitionMetadata.ExpiresOn from AuthenticationResult by Neha Bhargava (@neha-bhargava) in #3904
• Test: consolidate MI E2E test onto shared Msal_Integration_tests UAMI by Ryan Auld (@RyAuld) in #3926
• docs: Credential architecture internals documentation by Gladwin Johnson VR (@gladjohn) in #3886
• Potential fix for code scanning alert no. 35: Missing cross-site request forgery token validation by Gladwin Johnson VR (@gladjohn) in #3929
• Register IAuthorizationHeaderProvider2 in DI by Neha Bhargava (@neha-bhargava) in #3927
• Bump Microsoft.Identity.Client to 4.86.0 by Neha Bhargava (@neha-bhargava) in #3931
• Split PR pipeline into independent net8 stages; add MI E2E stage on MSALMSIV2 by Iarek Kovtunenko (@iarekk) in #3933
• Run missing unit test projects in the ADO PR build by Iarek Kovtunenko (@iarekk) in #3934
• Revert PRs #3933 and #3934: restore single-job PR pipeline by Gladwin Johnson VR (@gladjohn) with @Copilot in #3936

Full Changelog: 4.12.2...4.13.0

Bug fixes

• Make the Microsoft.Identity.Client.KeyAttestation dependency conditional on modern .NET (.NETCoreApp) targets. It transitively pulls the native-only Microsoft.Azure.Security.KeyGuardAttestation package, which ships no .NET Framework/netstandard-compatible assets and broke NuGet restore for .NET Framework (packages.config) projects. Microsoft.Identity.Web.Certificateless now multi-targets, and .NET Framework consumers use the netstandard2.0 asset without this dependency. See #3894.

Bug fixes

• Preserve ManagedIdentity when converting AcquireTokenOptions to TokenAcquisitionOptions in TokenAcquirer. Previously the ITokenAcquirer.GetTokenForAppAsync / GetTokenForUserAsync paths silently dropped ManagedIdentity and fell back to the confidential-client path, breaking managed-identity mTLS PoP (e.g. MISE Native). See #3914.

Behavior changes

• Sidecar: outbound HTTP redirects suppressed by default. The sidecar no longer follows outbound HTTP redirects; a new opt-in Sidecar:AllowOutboundRedirects flag (default false) restores the previous behavior. See #3906.
• Sidecar: per-request isolation of downstream API options. Downstream API options resolved from the singleton IOptionsMonitor are now cloned per request (including fresh ExtraParameters / ExtraHeaderParameters / ExtraQueryParameters dictionaries), preventing request-scoped values from leaking across requests or racing under concurrency. See #3919.

Fundamentals

• Build the solution in the PR pipeline before running tests. See #3911.
• Restore OWIN 5.7.1 packages from the internal IDDP feed in the PR pipeline. See #3912.
• Run the PR pipeline on the Wilson pool so integration/E2E tests can access the lab KeyVault. See #3913.