Description

Authorization bypass through user-controlled key in Entra Device Registration allows an unauthorized attacker to elevate privileges over a network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "10.0",
  "pubDate": "2026-11-06T23:17:20.557Z",
  "pubdate": "2026-11-06T23:17:20.557Z",
  "executiveSummary": "This vulnerability involves an authorization bypass within the Entra Device Registration process, enabling unauthorized actors to elevate privileges within the network.\nThe flaw stems from insufficient validation of user-controlled keys during the device registration flow, which allows an attacker to manipulate authentication tokens or registration state.\nBy exploiting this weakness, an unauthorized user can bypass standard security controls, potentially gaining the identity of a registered device or escalating their current privilege level.\nAffected systems include Microsoft Entra components responsible for handling device identity and registration logic.\nThe primary risk implication is the potential for unauthorized access to corporate resources, data exfiltration, or lateral movement within the environment.\nAttackers do not necessarily require prior administrative credentials if they can intercept or influence the registration process, provided they can supply a malicious or manipulated key that the system erroneously accepts as authoritative.",
  "technicalDetails": "The root cause of the vulnerability resides in the Entra Device Registration service's handling of cryptographic keys provided by clients during the registration handshake.\nSpecifically, the service fails to strictly validate the provenance and legitimacy of user-supplied keys, allowing for a key-injection scenario or the association of an unauthorized key with a targeted identity.\nThe exploitation flow initiates when an attacker triggers the device registration protocol. During this exchange, the attacker injects a user-controlled key that the service incorrectly interprets as a valid, trusted credential for an established identity or a privileged security principal.\nBy manipulating the key parameters, the attacker bypasses the authorization checks that normally ensure only authorized users or hardware can register a device within the tenant.\nOnce the malicious key is accepted by the Entra backend, the service generates an authentication token associated with the spoofed or elevated context.\nThe attacker then leverages this token to authenticate as a highly privileged identity, effectively bypassing conditional access policies and multi-factor authentication requirements that would typically be enforced for such accounts.\nThe attack is characterized by the lack of integrity verification on the registration payload, meaning the backend component performs a blind acceptance of the key material without verifying the attestation of the underlying hardware or the legitimacy of the request context.\nBecause the registration process is accessible over the network to facilitate remote device management, the vulnerability is exposed to any actor capable of interacting with the Entra public-facing registration endpoints.\nPost-exploitation, the attacker gains persistent access to the network under the guise of an authorized device. This facilitates unauthorized access to cloud-based applications and on-premises resources synchronized via the Entra framework.\nThe impact is significant, as it effectively invalidates the trust model established by Entra for device-based identity, allowing for widespread unauthorized privilege escalation across the affected tenant infrastructure."
}