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Security researcher Haakon Wik Gulbrandsrud reports finding five vulnerabilities in Azure API Connections that he says enabled full cross-tenant compromises of connected services. He says the findings earned $200,000 in rewards; the supplied report does not identify Microsoft’s response to each issue or establish the scope of affected customer data.
Security researcher Haakon Wik Gulbrandsrud says he found five vulnerabilities in Azure API Connections that allowed attackers to cross tenant boundaries and access services linked to other customers’ connections. His October 2026 report says the findings earned $200,000 in rewards, and describes potential access to services including Key Vault and Azure SQL; the supplied material does not establish how many customers were affected or whether any were exploited outside testing.
API Connections are part of Azure Logic Apps, where they mediate calls from workflows to connected backend services. Gulbrandsrud’s account describes a flow involving Azure Resource Manager (ARM), a shared Azure API Management service and a connector’s configured credentials. He says the vulnerabilities let a caller make the service operate on a connection belonging to another tenant, potentially using that connection’s access to its backend.
The report says the five findings provided the same basic capability, though the supplied excerpt does not detail all five vulnerabilities or identify the exact affected connectors. The researcher says the potential targets include Key Vaults and Azure SQL databases, as well as external services such as Jira and Salesforce. Those examples describe possible connected backends, not evidence that all listed services or customer accounts were accessed.
As an example from earlier work in the series, Gulbrandsrud describes using a path-traversal technique through an ARM DynamicInvoke request to retrieve a secret from a Key Vault in another tenant. He says Microsoft marked that earlier issue fixed a couple of weeks after he reported it, but he questioned whether the change addressed the underlying cross-connection authorization problem. The current report’s supplied text ends while discussing code he extracted from a Logic App host, so it does not provide the full technical account or a complete remediation timeline for all five findings.
Cross-Tenant Access to Connected Services
The reported issue matters because API Connections can hold or use credentials for services outside the workflow itself. If a caller can make a shared service apply another tenant’s connection credentials to a request, the exposure may extend beyond Azure resources to the data and operations available through the connected account. The potential impact depends on the permissions attached to each connection.
Gulbrandsrud notes that customers can limit backend permissions, which would constrain the damage from a compromised connection. He argues that this may not be common, and says OAuth connections can use the token of the person who originally configured them. These are the researcher’s assessments; the report provides no independent measurement of how customers configure permissions. The distinction matters: a cross-tenant flaw could create a route to access, but the connected credentials determine what that route can reach.
The findings also raise a platform-level security question about authorization boundaries in shared infrastructure. Fixing request paths or input validation may block a particular exploit form, while leaving the underlying issue if the service does not consistently verify that a caller is authorized to use a specific connection. The report’s account makes that a concern for Microsoft and customers to evaluate, rather than a confirmed description of the status of every vulnerability.
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How API Connections Route Requests
In the architecture described by the researcher, a Logic App sends a request through a shared API Management instance. That service checks the connector definition, exchanges the incoming credential for the configured backend credential, then sends the request onward. Because the backend credential is associated with the connection, the security boundary depends on the system applying the correct connection and authorization checks.
Gulbrandsrud says ARM endpoints, including DynamicInvoke and an extensions/proxy route, can send requests through this architecture. He argues that a caller who can cause the service to select another connection may gain access to that connection’s backend. His earlier report in the series described a Key Vault access example; the October report presents five further vulnerabilities as sharing the same basic capability. The source material does not include Microsoft documentation or a response from the company to independently confirm the architecture or the reported findings.
“API Connections allow anyone to fully compromise any other connection worldwide, giving full access to the connected backend.”
— Haakon Wik Gulbrandsrud, security researcher
Scope and Fix Status Remain Unclear
The supplied report material does not list all five vulnerabilities, their individual disclosure dates, affected connector types, or the fixes applied to each. It also does not include a statement from Microsoft, a formal advisory, or information about whether exploitation occurred in the wild. The researcher’s earlier example shows a successful test against a Key Vault, but does not establish access to unrelated customer data.
It is also unclear how many tenants or connected services were vulnerable, what permissions were present on the tested connections, and whether customers needed to take any action. Gulbrandsrud says one previously reported issue was marked fixed within weeks, but the excerpt does not establish whether that fix covered the later findings or whether Microsoft considers all five resolved. The report’s claim of broad potential access should not be treated as evidence of a confirmed breach or universal exposure.
Disclosure and Remediation Details Needed
The next useful milestones are publication of the report’s complete technical details, any Microsoft advisory or response, and clarification of remediation status for each finding. Gulbrandsrud also says he presented the research at Blue Hat Asia 2026 and planned to add a link when recordings became available. That recording may provide further detail, but no release date is given in the supplied material.
Azure customers using Logic Apps API Connections should consult Microsoft’s security guidance and their own service configuration for relevant notices, rather than assume exposure or safety from the report alone. The specific questions to resolve are whether any connection types require customer action and whether backend credentials were adequately restricted. Until those details are public, the scale of risk and the status of all five reported vulnerabilities remain unsettled.
Key Questions
What did the researcher report?
Haakon Wik Gulbrandsrud says he found five vulnerabilities in Azure API Connections that could let a caller use another tenant’s connection to reach its connected backend. The supplied report does not provide full details for all five findings.
Which services could be affected?
The researcher names Azure Key Vault and Azure SQL, along with external services such as Jira and Salesforce, as examples of possible connected backends. The report does not say that every listed service was accessed or that all customers were affected.
Did the vulnerabilities expose customer data?
The researcher describes a test that retrieved a Key Vault secret from another tenant in an earlier report. The supplied material does not establish real-world exploitation, the number of affected customers, or the scope of any customer data exposure.
Did Microsoft fix the vulnerabilities?
Gulbrandsrud says an earlier vulnerability was marked fixed a couple of weeks after he reported it. The supplied report does not confirm the remediation status of all five findings or include a Microsoft statement.
Source: binarysecurity.no
