Description

Authentication bypass using an alternate path or channel in Microsoft Entra ID allows an unauthorized attacker to elevate privileges over a network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.1",
  "pubDate": "2026-09-03T23:17:19.693Z",
  "pubdate": "2026-09-03T23:17:19.693Z",
  "executiveSummary": "This vulnerability is categorized as an authentication bypass via an alternate path or channel, specifically affecting Microsoft Entra ID (formerly Azure Active Directory).\nThe flaw permits an unauthorized attacker to circumvent standard identity verification mechanisms, facilitating unauthorized access to protected resources.\nThe impact includes critical privilege escalation, allowing attackers to operate with the permissions of legitimate users or administrative accounts without valid credentials.\nThis vulnerability poses a significant risk to organizational identity infrastructure, potentially enabling unauthorized access to cloud resources, enterprise applications, and sensitive corporate data.\nExploitation requires the attacker to leverage unintended authentication paths or secondary channels to gain network-level access.\nThe inherent architecture of Microsoft Entra ID as a centralized identity provider makes this a high-severity concern, as it undermines the foundation of zero-trust security postures and conditional access policies.",
  "technicalDetails": "The vulnerability stems from a flaw in the authentication logic of Microsoft Entra ID where the system fails to adequately enforce identity validation across all supported communication channels or entry points.\nAn alternate path or channel vulnerability typically occurs when security controls—designed for the primary authentication endpoint—are not consistently applied to secondary endpoints, legacy APIs, or auxiliary authentication flows.\nThe root cause involves an inconsistency in the enforcement of security tokens or authentication assertions when an attacker initiates a request via an unconventional or secondary network path.\nIn a standard flow, Microsoft Entra ID requires valid primary credentials (e.g., password, MFA) to issue an access token. In this bypass scenario, the attacker intercepts or crafts a request to an alternate channel that inadvertently trusts unauthenticated or spoofed claims.\nAttack flow: First, the attacker identifies a non-standard endpoint or secondary protocol path within the Microsoft Entra ID infrastructure that bypasses the primary Identity Provider (IdP) gateway checks.\nSecond, the attacker crafts a malicious request that omits standard authentication headers or provides a malformed, yet accepted, authentication assertion.\nThird, the vulnerable component, failing to perform exhaustive validation on this specific channel, processes the request as a legitimate authenticated session, generating a valid security token or session context.\nConsequently, the attacker achieves unauthorized access to the target tenant, effectively bypassing Multi-Factor Authentication (MFA) and Conditional Access (CA) policies.\nPost-exploitation, the attacker can leverage the escalated privileges to perform lateral movement, data exfiltration, or persistence through the creation of new service principals or the modification of federated domain settings.\nSince this bypass occurs at the IdP level, the malicious activity may appear as legitimate user behavior in audit logs, complicating detection and forensic analysis.\nThe vulnerability does not require prior knowledge of the target's credentials, focusing instead on the architectural misconfiguration within the authentication handshake process for specific, exposed channels."
}