CVE-2025-66390
48Vexday Risk Score
No sign of exploitation. It has a public proof of concept.
ssvc Attendcvss 9.8epss 0.3%
from disclosure to weapon15 days
Published on NVDJul 21
1st PoC+15d
exploitation probability
0.3%top 73% of all CVEs
observed exploitation
nono source reports it
1 public exploit(s)
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).
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected products
n/a · n/apublic PoCs found — 1
githubgithub.com/dz-y/Azure-APIM-Dev-Portal-Signup-Bypass★ 0⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.