Starbucks: Multiple Subdomain takeovers via unclaimed instances

Hacker @benoculars was able to successfully faciliate multiple subdomain takeovers by taking advantage of a process flow to use some of the space provided for germany.openapi.starbucks.com, psv.openapi.starbucks.com, stage-psv.openapi.starbucks.com, and test-psv.openapi.starbucks.com. While we we...