Microsoft: WCF/WIF SAML Token Authentication Bypass Vulnerability
An authentication bypass vulnerability exists in Windows Communication Foundation (WCF) and Windows Identity Foundation (WIF), allowing signing of SAML tokens with arbitrary symmetric keys. This vulnerability allows an attacker to impersonate another user, which can lead to elevation of privileges. The vulnerability exists in WCF, WIF 3.5 and above in .NET Framework, WIF 1.0 component in Windows, WIF Nuget package, and WIF implementation in SharePoint. An unauthenticated attacker can exploit this by signing a SAML token with any arbitrary symmetric key. This security update addresses the issue by ensuring all versions of WCF and WIF validate the key used to sign SAML tokens correctly.
Microsoft .NET Framework 4.5.2 on Windows RT 8.1,Microsoft .NET Framework 3.5 AND 4.8 on Windows Server, version 1903 (Server Core installation),Windows Server, version 1903 (Server Core installation),Microsoft SharePoint Enterprise Server 2016,Microsoft SharePoint Server 2019,Microsoft .NET Framework 4.8 on Windows RT 8.1,Windows Server 2016,Windows Server 2012,Windows 10,Windows Server 2019