The WiredTiger code has not historically validated commit and durability timestamps at transaction commit if they were set before the transaction commit. That is, timestamps were validated when they were set, rather than always being checked at transaction commit. This could lead to the following sequence:

1. a transaction setting the commit timestamp before the stable timestamp
2. stable being moved past the commit timestamp
3. the transaction committing

Which would result in a transaction committing before the stable timestamp.

This is fixed in WT-8990, but results in MDB patch build failures.

This is a data consistency problem and deserves a reasonably high priority.