Vercel OAuth Integration Breach Third-Party Compromise | MSSP Advisory

Vercel suffered a breach through a compromised third-party OAuth integration that provided attackers direct access to their environment and potentially downstream customer data. The attack vector shows how OAuth applications can bypass traditional security controls when the third-party service gets compromised. OAuth integrations often maintain persistent access tokens with broad permissions across connected systems.

Your RMM and PSA tools likely have dozens of OAuth integrations for automation, monitoring, and client management that create the same exposure Vercel faced. Client environments running productivity suites, development platforms, and SaaS applications with OAuth sprawl become accessible through any single compromised integration, and you need to audit what has access to what before your clients ask why their data leaked through a service they never heard of.

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