EUVD-2026-54326
GHSA-c89r-fxpx-x3w6
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Network-reachable signature-verification/JWT bypass needs no privileges or interaction (PR:N/UI:N/AC:L), and forged admin access yields high C/I/A over the tenant.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Improper verification of cryptographic signature in Microsoft 365 Admin Center allows an unauthorized attacker to elevate privileges over a network.
AnalysisAI
Privilege elevation in Microsoft 365 Admin Center allows a remote, unauthenticated attacker to gain elevated permissions by exploiting improper verification of a cryptographic signature (CWE-347), consistent with the vendor-supplied 'Authentication Bypass' and 'JWT Attack' tags. The maximal 9.8 CVSS with a fully network-reachable, no-privilege, no-interaction vector makes this a critical bypass of the admin portal's trust boundary. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Per the CVSS vector (AV:N/AC:L/PR:N/UI:N), no special conditions are required beyond network reachability to the Microsoft 365 Admin Center service - no authentication, no privileges, and no user interaction. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The signals are largely aligned toward high priority but incomplete on real-world exploitation. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Because Microsoft 365 Admin Center is a Microsoft-operated cloud service, the fix is deployed server-side by Microsoft and generally requires no customer installation - Patch available per vendor advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62873; confirm remediation status and any tenant-side action directly in that advisory. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Conduct an immediate audit of Microsoft 365 Admin Center access logs to identify anomalous sign-ins or unauthorized privilege grants; restrict Admin Center access to a hardened, network-isolated administrative workstation and enable enhanced logging of all admin activities. …
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External POC / Exploit Code
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