Azure API Connections flaws allow full cross-tenant compromise

Overview

Updated 2 hours ago

A Norwegian security firm published details of five critical vulnerabilities in Azure API Connections, the credential store for Microsoft's Logic Apps service. Each flaw let an attacker in one Azure tenant reach into another tenant's connected services: Key Vaults, SQL databases, Jira, Salesforce.

All five bugs sit in a shared credential-exchange layer that swaps a caller's token for a stored backend token. Microsoft fixed each reported issue, and the researcher earned $200,000 in bounties, but the fixes were bypassed repeatedly before they held.

Why it matters

Any Azure customer using API Connections could have stored service credentials taken over by an attacker in another tenant.

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Key Indicators

Critical cross-tenant vulnerabilities

All found in Azure API Connections credential exchange.

$200,000

Bounty paid by Microsoft

Total across all five vulnerability reports.

Endpoints on the DynamicInvoke path

One public, three undocumented; all blocked by Microsoft after bypass.

Voices

Curated perspectives — historical figures and your fellow readers.

People Involved

Haakon Wik Gulbrandsrud

Security researcher at Binary Security

Disclosed five critical Azure vulnerabilities; received $200,000 in bounties

Organizations Involved

Microsoft

Technology company

Patched all five reported vulnerabilities

Operates Azure, the cloud platform where the vulnerabilities were found.

Binary Security

Security research firm

Disclosed the vulnerabilities; received bounties

Norwegian security firm that found and reported the five vulnerabilities.

Timeline

August 2025 October 2026

2 events Latest: Today

October 2026
Five Full Cross-Tenant Compromises published
Today Disclosure

Binary Security documents five critical flaws, including several fix bypasses. Microsoft paid $200,000 in bounties.
Today
August 2025
First cross-tenant compromise disclosed
Disclosure

Binary Security publishes a full cross-tenant compromise of Azure API Connections using the DynamicInvoke endpoint.
August 2025

Scenarios

Microsoft hardens API Connections against further bypasses

Likely Resolves by Apr 30, 2027

Discussed by: Binary Security's write-up, which notes Microsoft fixed each report but did not change the underlying architecture

Microsoft either removes the host.api.RuntimeUrl parameter entirely or tightens validation to eliminate path-normalization bypasses. If no new bypass surfaces within six months, the fixes may finally hold.

Another cross-tenant bypass emerges in API Connections

Possible Resolves by Apr 30, 2027

Discussed by: The fix-bypass pattern documented in Binary Security's write-up, where each patch was followed by a new attack

Every Microsoft fix so far was bypassed through path normalization, undocumented endpoints, or the RuntimeUrl parameter. A new route through the shared credential-exchange layer may surface from the same researcher or another.

Microsoft redesigns API Connections to remove shared credential exchange

Unlikely Resolves by Oct 30, 2027

Discussed by: Binary Security's write-up, which identifies the shared API Management credential-exchange layer as the root cause of all five flaws

Microsoft replaces the shared Azure API Management credential exchange with per-tenant isolation or a different trust model. This would address the underlying architecture that made five distinct attack chains possible.

Historical Context

One moment from history that rhymes with this story — and how it unfolded.

2025

Azure Container Instances cross-tenant access (Palo Alto Networks)

Palo Alto Networks researchers found a vulnerability enabling cross-tenant access in Azure Container Instances, another shared Azure service. The finding was discussed in Hacker News threads about the earlier Azure API Connections research.

Then

Microsoft patched the vulnerability after disclosure.

Now

It added to a pattern of Azure shared services with tenant-isolation flaws.

Why this matters now

Shows Azure's multi-tenant isolation failures are not unique to API Connections; shared services across the platform have similar trust-boundary weaknesses.