Azure API Connections: Five Cross-Tenant Hacks, $200K
Original: Azure's Weakest Link – Five Full Cross-Tenant Compromises
Why This Matters
Shared multi-tenant infra flaws can expose thousands of enterprise backends at once.
Security researcher Haakon Wik Gulbrandsrud disclosed five separate cross-tenant compromise vulnerabilities in Azure API Connections, earning $200,000 in bug bounties and presenting findings at Blue Hat Asia 2026.
Azure API Connections, a component of Azure Logic Apps, has a systemic architectural flaw that allows an attacker to hijack any other user's connection worldwide — giving full access to connected backends including Key Vaults, Azure SQL databases, Jira, and Salesforce.
Researcher Haakon Wik Gulbrandsrud of Binary Security has now published a third installment in his series on the issue, detailing five distinct vulnerabilities that each yield the same powerful primitive: full cross-tenant compromise. Together they earned him $200,000 in Microsoft bug bounties.
The root problem lies in how Azure's shared API Management (APIM) instance handles connections. When a Logic App action fires, APIM validates the request against an OpenAPI definition, then swaps the caller's token for the backend service's configured credentials before completing the call. If an attacker can redirect that token exchange to target a victim's connection instead of their own, they inherit full access to the victim's backend.
Microsoft's own ARM REST API endpoints — specifically `DynamicInvoke` and `/extensions/proxy/` — can be used to query APIM directly, bypassing normal routing. The only real barrier to exploitation has been input validation layered onto individual systems, but as Gulbrandsrud notes, edge cases keep slipping through.
OAuth connections are particularly exposed: the token is always that of the user who initially created the connection. API key connections fare no better, since minimal-privilege scoping is rarely enforced in practice.