What breaks when spreadsheet formulas can reach host execution?

The spreadsheet stops being a content container and becomes an execution surface. Once formulas can call host primitives, the attacker can reach files, environment secrets, and network resources tied to the runtime. That is why the control boundary must sit around the formula engine itself, not around the document format. Ultimate Guide to NHIs , Lifecycle Processes for Managing NHIs helps teams think about lifecycle and privilege scope around non-human execution.