CVE-2026-70005 in Active Directory Federation Services
Summary
by MITRE • 10/14/2026
Weak authentication in Active Directory Federation Services (AD FS) allows an unauthorized attacker to bypass a security feature over a network.
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Analysis
by VulDB Data Team • 10/14/2026
Active Directory Federation Services serves as a critical component in modern enterprise identity management architectures, facilitating single sign-on and federated authentication across organizational boundaries. The vulnerability described involves a weakness in the authentication mechanisms inherent to this service, specifically allowing an unauthorized actor to circumvent established security controls when interacting with the system over a network. This type of flaw typically stems from improper validation of credentials or tokens during the federation protocol exchange, which is fundamental to how AD FS verifies user identity before granting access to protected resources.
The technical nature of this weakness often relates to flaws in how authentication requests are processed and validated against security policies. In many such scenarios, an attacker may exploit insufficient checks on incoming authentication assertions or fail to properly enforce multi-factor authentication requirements during specific federation flows. By manipulating the sequence of authentication steps or injecting malformed data into the protocol stream, a malicious actor can trick the service into accepting invalid credentials as valid ones. This bypasses the intended security feature that would normally restrict access based on strict identity verification protocols, effectively allowing unauthorized entry without possessing legitimate user privileges.
From an operational perspective, the impact of this vulnerability is severe because it compromises the integrity of the entire federated trust relationship. If an attacker can successfully bypass authentication in AD FS, they gain the ability to impersonate any user or service account that relies on this federation endpoint for access. This leads directly to unauthorized data exposure, as sensitive corporate information becomes accessible to entities without proper clearance. Furthermore, it enables lateral movement within the network, allowing the attacker to pivot from a compromised external identity into internal systems and domain controllers, potentially leading to full infrastructure compromise if left unaddressed.
This vulnerability aligns with Common Weakness Enumeration categories such as CWE-287 Improper Authentication or CWE-306 Missing Authentication for Critical Function, depending on the specific implementation details of the bypass mechanism. In terms of adversary tactics, it maps closely to MITRE ATT&CK techniques related to Credential Access and Initial Access, specifically those involving phishing or exploiting authentication flaws to gain initial footholds in a network environment. The ability to bypass security features over the network places this risk squarely within the realm of remote exploitation, making it accessible to attackers who do not require prior local access to the target system.
Mitigation strategies must focus on immediate patching and configuration hardening. Organizations should apply the latest cumulative updates provided by Microsoft for Active Directory Federation Services to address known authentication bypass flaws. Additionally, administrators should review federation trust configurations to ensure that only necessary protocols are enabled and that strict validation rules are applied to incoming SAML assertions or other token types. Implementing conditional access policies through Azure AD Identity Protection can add an additional layer of verification, requiring multi-factor authentication for all federated logins regardless of the underlying protocol behavior. Regular auditing of sign-in logs is also essential to detect any anomalous patterns that might indicate exploitation attempts in real time.