Acquiring enough voting power to pass a proposal that benefits the attacker, rather than exploiting a code defect.
Why it matters
Nothing is broken; the protocol does what its holders instructed. Where voting power can be borrowed within one transaction via a flash loan and execution is immediate, the cost of a majority collapses to a fee.
What you can check
Governance parameters are usually readable from the governance contract: quorum, proposal threshold, voting period, and whether execution is delayed. The combination that matters is how much voting power passes a proposal and how long the protocol has to react before it executes.
Where it showed up
Records in the Incident Tracker that turn on this: Beanstalk governance flash loan.
Not advice. Definitions are for understanding, not instruction. Nothing here is financial, legal, tax or security advice.