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⚙️ How CVE-2026-42901 Works
The flaw centers on the Agent ID Administrator role in Microsoft Entra ID, intended for managing AI agent identities. This built-in role was implemented using standard Entra service principals. However, due to improper access scoping, a user assigned this role could take ownership of any service principal across the tenant, including those far outside the intended scope of AI agent management.
An attacker, after exploiting this vulnerability, could claim ownership over a highly privileged service principal. Once they control it, they can generate their own credentials (e.g., a client secret or certificate) and authenticate as that principal. This effectively allows them to inherit all of the service principal’s existing permissions across the tenant. The attacker could then compromise CI/CD pipelines, Microsoft Graph integrations, cloud infrastructure, or even escalate to global administrator-level privileges in the target environment.
📋 DailyCVE Form
Platform: Microsoft Entra ID
Version: All tenants
Vulnerability :Privilege Escalation
Severity: Critical (10.0)
date: 2026-05-22
Prediction: Already patched (2026-04-09)
🔬 What Undercode Say: Analytics
The `Agent ID Administrator` role’s permissions were not strictly scoped to agent-specific objects. This led to a “scope overreach” where the role could modify security principals it shouldn’t have access to. The attack path can be modeled as:
1. An attacker compromises an account with the `Agent ID Administrator` role.
2. The attacker identifies a high-value target, e.g., a service principal `A` used for infrastructure automation.
3. The attacker uses Microsoft Graph API to add themselves as an owner of service principal A.
The following PowerShell command, using the Microsoft Graph PowerShell SDK, replicates the malicious action an attacker would have performed prior to the patch. This command would add an owner to a targeted service principal:
Connect-MgGraph -Scopes "Application.ReadWrite.All", "Directory.ReadWrite.All" $ServicePrincipalId = "target-serviceprincipal-id" $OwnerUserId = (Get-MgUser -UserId "[email protected]").Id New-MgServicePrincipalOwnerByRef -ServicePrincipalId $ServicePrincipalId -BodyParameter @{ "@odata.id" = "https://graph.microsoft.com/v1.0/users/$OwnerUserId" }
After the patch, any attempt to assign ownership of a non-agent service principal using the Agent ID Administrator role results in a “Forbidden” (HTTP 403) error.
💀 Exploit
- Gain control of an Entra ID user assigned the `Agent ID Administrator` role.
- Query the tenant to discover high-privilege service principals (e.g., those with `Application Administrator` or `Global Administrator` roles).
- Use Microsoft Graph API to change the target service principal’s ownership to the attacker-controlled account.
- Generate new credentials (a password or certificate) for the compromised service principal.
- Authenticate to Entra ID as that service principal using the new credentials, inheriting all of its permissions.
🛡️ Protection from this CVE
- Apply Microsoft’s Patch: Microsoft fully remediated the vulnerability across all cloud environments on April 9, 2026.
- Audit Role Assignments: Review all assignments of the `Agent ID Administrator` role and remove it from any unnecessary or suspicious accounts.
- Audit AuditLogs: Search for unexpected service principal ownership changes or new credential creation events.
- Enforce Least Privilege: Strictly limit the assignment of highly privileged roles to only essential personnel.
- Rotate Credentials: Rotate the credentials (keys/secrets) for any sensitive service principal that may have been exposed.
- Implement PIM: Use Privileged Identity Management (PIM) to require approval and time-bound activation of privileged roles.
💥 Impact
- Critical (CVSS 10.0). Unauthorized tenant-wide privilege escalation.
- Complete takeover of high-privilege service principals, leading to full control of CI/CD, cloud infrastructure, and directory-level permissions.
- Potential for lateral movement and data breach across the Microsoft cloud environment.
- The role was not clearly labeled as highly privileged, increasing the risk of accidental or unsafe assignment by admins.
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Sources:
Reported By: nvd.nist.gov
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