CVE-2012-3371: OpenStack Nova Scheduler denial of service through scheduler_hints

The vulnerability stemmed from making individual database calls (compute_api.get()) for each UUID in scheduler_hints. The pre-patch implementation in DifferentHostFilter and SameHostFilter's host_passes methods iterated through UUIDs using _affinity_host(), which performed a separate database lookup for each UUID. This created a linear scaling problem where repeated UUIDs would trigger multiple redundant database queries. The commit 034762e replaced this pattern with a bulk lookup (compute_api.get_all()) in _all_hosts(), demonstrating the vulnerable pattern was in these filter methods and their dependency on _affinity_host.