CVE-2025-66390: Microsoft Azure API Management · Improper Access Control
Source CVE Database V5
Not known to be exploited · CVSS 9.8 Critical · patch available : patch affected systems as a priority.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 37% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 21 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
AI-suggested
Since this is a cloud-hosted service, Microsoft manages remediation server-side. A patch is available for this issue. Users should monitor the vendor advisory for patch deployment status and apply any recommended updates or configuration changes as provided by Microsoft. No additional mitigation steps are specified by the vendor, as the issue is considered a configuration/state problem rather than a direct vulnerability affecting tenant isolation.
Description
Microsoft Azure API Management through 2025-10-17 has a vulnerability where self-service signup enabled in one tenant can be reused by an attacker to register in another tenant that has signup disabled at the UI level. This occurs because the underlying API endpoint accepts cross-tenant requests based on the Host header, ignoring the UI setting. The vendor states this is a configuration/state issue and does not cross a security boundary or affect tenant isolation. The service is cloud-hosted, and a patch is available.