CVE-2025-66390

EIP tracks 1 public exploit for CVE-2025-66390. PoCs published by dz-y.

AI-analyzed exploit summary This PoC exploits an authentication bypass in Azure API Management (APIM) Developer Portal by directly invoking the backend `/signup` API endpoint, which remains active even when self-service signup is disabled in the UI. The script solves a proof-of-work (PoW) challenge client-side to complete the registration process, enabling unauthorized account creation.

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).