CVE-2026-58529
Summary
by MITRE • 07/14/2026
Out-of-bounds read in Active Directory Federation Services (AD FS) allows an authorized attacker to disclose information over a network.
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Analysis
by VulDB Data Team • 07/14/2026
This vulnerability represents a critical security flaw in Microsoft Active Directory Federation Services that enables unauthorized information disclosure through network-based attacks. The out-of-bounds read condition occurs when AD FS processes certain authentication requests, allowing an attacker with valid credentials to manipulate input data in ways that trigger memory access violations. This specific weakness falls under the CWE-125 vulnerability category, which describes out-of-bounds read conditions where programs access memory locations beyond allocated buffers or arrays. The flaw exists in the authentication processing pipeline of AD FS, particularly when handling federated identity requests from relying parties.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with potential access to sensitive authentication data and user credentials stored within the federation service. Attackers can exploit this issue by crafting specially formatted authentication requests that cause the AD FS server to read memory locations containing confidential information such as user session tokens, authentication certificates, or internal system details. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under the T1566 initial access category, specifically targeting credential access through exploitation of authentication services. The attack vector requires network connectivity and valid authentication credentials to the AD FS service, making it particularly dangerous in environments where internal network segmentation is not properly enforced.
From a security perspective, this vulnerability creates significant risk for organizations relying on AD FS for federated identity management, as it allows attackers to escalate privileges and potentially gain access to additional systems within the domain. The information disclosure can lead to further exploitation opportunities including credential harvesting, session hijacking, or privilege escalation attacks against other services within the federated environment. Organizations should implement immediate mitigations including applying Microsoft security patches, implementing network segmentation controls to limit access to AD FS servers, and monitoring for anomalous authentication patterns that could indicate exploitation attempts.
The vulnerability demonstrates the importance of proper input validation in authentication services and highlights the need for robust memory safety practices in enterprise identity management systems. Security teams should conduct comprehensive assessments of their AD FS deployments to identify systems potentially affected by this issue and implement appropriate controls including network access restrictions, enhanced monitoring, and regular security updates. This type of vulnerability represents a classic example of how seemingly minor input validation flaws can lead to significant security implications in critical infrastructure components that handle sensitive authentication data across enterprise networks.