Cross-tenant administrator access via unbound Actor tokens
Published Sep 4, 2025 · Updated Feb 26, 2026
Improper authentication in Microsoft Entra allows remote attackers to gain Global Administrator access across tenants via Actor tokens. The legacy Azure AD Graph accepted unsigned impersonation tokens without verifying that the Actor token's originating tenant matched the target tenant. Exploitation required an attacker-controlled tenant and a victim tenant ID plus a discoverable or brute-forceable netId, enabling directory reads and writes as Global Administrator.
Summary
What happened
Improper authentication in Microsoft Entra allows remote attackers to gain Global Administrator access across tenants via Actor tokens. The legacy Azure AD Graph accepted unsigned impersonation tokens without verifying that the Actor token's originating tenant matched the target tenant. Exploitation required an attacker-controlled tenant and a victim tenant ID plus a discoverable or brute-forceable netId, enabling directory reads and writes as Global Administrator.
The record
- CVE
- CVE-2025-55241
- Published
- Sep 4, 2025
- Updated
- Feb 26, 2026
- Vendor
- Microsoft
- Product
- Microsoft Entra
- Classifications
- CWE-287, T1550.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 4, 2025CVE publishedPublication date reported by the CVE source.
- Feb 26, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=-
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
- Actor-token cross-tenant impersonation demonstrationfunctional · demonstrated
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Technologies
Your stack
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Your stack
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