Azure API Connections Flaws Enabled Secret Theft and Cross-Tenant Access

Researchers disclosed two severe flaws in Azure API Connections that exposed the trust model behind Microsoft’s managed connectors and could let attackers abuse authenticated connections to reach protected backend services. In the first issue, users with only Reader access to a connection could reportedly send authenticated requests through undocumented /extensions/proxy endpoints and inherit the connection’s existing privileges, exposing data from services including Azure Key Vault, Azure SQL, Jira, Slack, Salesforce, Azure Storage, Defender ATP, and Google services. The researcher also reported that the Jira connector could be abused for SSRF and API token theft when APIToken authentication was configured.

A second report alleged that Azure’s globally shared API Management architecture for connectors enabled cross-tenant compromise through Azure Resource Manager’s undocumented DynamicInvoke endpoint. By combining a custom connector with path traversal, an attacker could reportedly make privileged requests against arbitrary victims’ API Connections and potentially control or extract data from connected backends with inherited administrator-level access. The researcher said Microsoft confirmed the issue within days, deployed mitigations within a week, and later awarded a $40,000 bounty, although the published write-up warned the fix relied largely on blocking ../ and encoded variants and might be bypassable.