Microsoft Entering ID: vulnerability CVE-2026-69836 exploited and mitigated

Microsoft has reported the existence of a maximum gravity vulnerability in its cloud identity service - Microsoft Entering ID - listed as CVE-2026-69836 and with a CVSS score of 10.0. The company claims that the failure has been exploited in real environments and that, according to its internal investigation, it has already been mitigated by Microsoft, so it does not require immediate customer actions. The public report attributes the discovery to Robert Fitzztrick, the chief security engineer.

Confirmed facts: Microsoft describes vulnerability as a case of deerialization of unreliable data in Enter ID that allows remote execution of code (CERs) over the network. The warning identifier is CVE-2026-69836 (CVSS 10.0) and the company itself has reported that it detected active exploitation "in nature" and that it implemented mitigation to neutralize the risk, indicating that users should not make changes in their environments according to the official statement. The entry into the NIST (NVD) vulnerability repository and the Microsoft Security Response Center (MSRC) page contain the public follow-up of this CVE and the manufacturer's technical note ( NVD - CVE-2026-69836, MSRC - CVE-2026-69836).

Technically, unsafe deerialization occurs when an application converts received data (e.g. from the network or a service) into executable objects without verifying their integrity or origin. When attackers control these data, they can manipulate the structure to inject code or objects with malicious behaviors that run in the context of the service that deerialization does. This type of failure can result not only in remote code execution, but also in denial of service or avoidance of access controls, depending on the nature of the component concerned. For a general explanation of this attack vector, see the OWASP community documentation on deerialization: OWASP - Deserialization of untrusted data.

What this means for organizations: Microsoft Entering ID (formerly Azure Active Directory) is the central identity service for the Microsoft ecosystem in the cloud; it controls authentication, tokens emission, unique login and application and user permissions. An CERs in this component can become a critical step for an attacker: it could potentially compromise the identity platform, falsify tokens, create or modify accounts, or remain in the environment with increased privileges. These effects depend on how the failure has been exploited and the extent of the operation within each holding, so the actual impact varies between organizations.

What Microsoft confirmed does not include technical details about the attacking agent, specific operating vectors, when the activity started, or whether the operation is still in progress. These points remain without public information, leaving several unknown:: who were the operators, what specific objectives they sought (e.g. access to post and data or deployment of persistent payload), how many tenants were affected and whether credentials or other devices were leaked. Until Microsoft publishes a more detailed forensic report, all claims about the scope and purpose of the attacks are estimates.

Real and plausible consequences: if the deerialization was successfully exploited against Entered ID instances in an organization, the likely consequences include the issuance of fraudulent tokens, commitment of administrative accounts, access to resources protected by Azure and persistence through application credentials or changes in roles and permits. However, there is no public confirmation that these scenarios have occurred in specific cases; what is known is that the vector is serious enough to reach the maximum CVSS score and that Microsoft considers that the operation has already taken place.

Concrete measures to be taken by technical managers: first, review Microsoft's official communication at MSRC and the Entrance Management Centre for instructions and status updates. Although Microsoft indicates that there is no need for customer action, it is prudent verify telemetry identity and authentication in search of anomalies. Recommended steps: check the login and audit records in Entre ID (Azure / Entre portal → Sign-ins / Audit Logs), search for unusual tokens activity (mass issue or from abnormal PIs), review recent assignments of privileged roles and changes in registered applications or delegation permits.

It is also advisable to force the revocation of sessions and tokens for high-risk or transactional sensitive accounts if suspicious activity is detected, to rotate application secrets and certificates where feasible, and to activate IMS alerts that point to atypical behaviors (for example, to create new credentials, consent to unusual applications, or out-of-time privileges elevations). If your organization uses integration with external suppliers or has applications that rely on Enter ID, review those endpoints and associated credentials.

General mitigation measures for managers and users: to maintain the multi-factor protection (MFA) enabled for all privileged accounts, to segment administration through access models with just-in- time and minimum privileges, and to use secure management stations (Prived Access Workstations). For end-users, practical recommendations are the usual: activate MFA, attend and report suspicious emails or application consent requests and do not reuse passwords.

Immediate operational actions for security equipment: confirm the service status on the Microsoft state portal and on the MSRC; export and preserve relevant login for possible forensic analysis; raise to Microsoft Support if operating evidence is detected in your tenant; and, in case of commitment confirmation, activate your incident response plan to contain, eradicate and recover services. For search criteria, prioritize role creation events, changes in main services (service principals), irregular tokens emission and abnormal sessions from unpublished locations.

In short, vulnerability is real and serious, Microsoft says it was exploited and has already applied mitigations, but there are crucial public details about the scope and the attackers. Until more forensic information is available, organizations should increase monitoring of identity telemetry, apply robust identity security controls and follow Microsoft's official instructions. Keep up-to-date communication with your service provider and incident response teams to respond quickly to any signs of commitment.