In Microsoft Azure API Management through 2025-10-17, when self-service signup (username/password Basic Authentication) is enabled in Tenant A, an attacker can reuse the registration flow by changing the hostname or tenant identifier to Tenant B, even when Tenant B has signup disabled at the UI level. In other words, disabling signup in the UI does not disable the underlying API endpoint (which still accepts cross-tenant requests based on the Host header). NOTE: The supplier states that they evaluated the report and determined it did not cross a security boundary (i.e., the observed behavior was a configuration/state issue rather than an exploitable product vulnerability affecting tenant isolation). NOTE: The supplier evaluated this report and determined that it did not cross a security boundary (i.e., the observed behavior was a configuration/state issue rather than an exploitable product vulnerability affecting tenant isolation).
History

Wed, 22 Jul 2026 16:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-284
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Tue, 21 Jul 2026 14:00:00 +0000

Type Values Removed Values Added
Description In Microsoft Azure API Management through 2025-10-17, when self-service signup (username/password Basic Authentication) is enabled in Tenant A, an attacker can reuse the registration flow by changing the hostname or tenant identifier to Tenant B, even when Tenant B has signup disabled at the UI level. In other words, disabling signup in the UI does not disable the underlying API endpoint (which still accepts cross-tenant requests based on the Host header). NOTE: The supplier states that they evaluated the report and determined it did not cross a security boundary (i.e., the observed behavior was a configuration/state issue rather than an exploitable product vulnerability affecting tenant isolation). NOTE: The supplier evaluated this report and determined that it did not cross a security boundary (i.e., the observed behavior was a configuration/state issue rather than an exploitable product vulnerability affecting tenant isolation).
References

cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published:

Updated: 2026-07-22T15:47:05.047Z

Reserved: 2025-11-28T00:00:00.000Z

Link: CVE-2025-66390

cve-icon Vulnrichment

Updated: 2026-07-22T15:19:03.139Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.