Microsoft Active Directory Federation Services Information Disclosure Vulnerability

A vulnerability in Active Directory Federation Services (ADFS) has been identified, allowing unauthorized attackers to locally disclose sensitive information. This issue arises from the insertion of confidential data, such as Single Sign-On (SSO) cookies, into ADFS log files.

Impact

Exploitation of this vulnerability could lead to unauthorized local disclosure of sensitive information, including SSO cookies, which could be used to impersonate users in ADFS.

Remediation

Users can apply the security update for this vulnerability, which is included in the October 2025 Monthly Rollup, available through the Microsoft Update Catalog. Specific update details can be found in the Microsoft Knowledge Base articles KB5066873, KB5066875, KB5066836, KB5066780, KB5066782, and KB5066586.