By Medha Cloud Security Desk
Microsoft has released a critical security update to address a flaw in its Entra ID (formerly Azure Active Directory) service that could have allowed attackers to impersonate global administrators and gain full access to cloud environments. The company confirmed that the issue, which affected token validation logic, was reported privately and has since been patched.
The vulnerability, identified as a token validation bypass, allowed specially crafted tokens to be accepted as legitimate within certain configurations of Entra ID. This loophole made it possible for attackers to escalate privileges across tenants, effectively impersonating highly privileged users and accessing sensitive data.
According to The Hacker News, the flaw represented one of the more dangerous identity-related weaknesses discovered this year. While there is no evidence of widespread exploitation, Microsoft acknowledged that advanced threat actors could have used the vulnerability in targeted attacks if left unpatched.
Security experts say the incident highlights the growing importance of identity security within multi-tenant cloud ecosystems. “When identity is compromised, everything downstream becomes vulnerable — applications, storage, and even monitoring tools,” said one security analyst familiar with the issue.
Microsoft has urged organizations to review their token-signing configurations, implement Conditional Access policies, and enable risk-based sign-in detection. Enterprises should also validate that all OAuth and OpenID Connect applications use strict token audiences to prevent unauthorized access.
Industry analysts note that token abuse has become a recurring theme in cloud compromise cases. Attackers increasingly target the “trust layer” — the invisible glue binding authentication and authorization across cloud apps. As a result, Microsoft and other cloud vendors have been reinforcing their identity frameworks with anomaly detection and AI-driven monitoring.
The Entra ID patch is part of Microsoft’s September 2025 security update cycle. Organizations using hybrid Active Directory should apply updates immediately and audit privileged tokens that may have been issued prior to the patch.
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