Verizon's 2026 Data Breach Investigations Report found that third parties played a role in 48% of breaches, up from 30% the year before. ISO 27001 requires certified companies to manage that risk through their suppliers, and guidance for its Annex A 5.21 control carries those security requirements past a company's vendors to their subcontractors. When an MSP outsources support, the outside engineers who log into a client's systems join that chain. The client has no contract with the outsourci...