It's possible to borrow, redeem, transfer tokens and exit markets with outdated collateral prices and borrow interest
>Oracle price of every market is updated on every action involving directly that market. We didn't update the prices of every market (secondarily) used in some operations to save gas, assuming the price would be valid (there are mechanisms in the Oracles to avoid the use of old prices). We'll monitor this topic to decide if our approach is enough or if we have to update the price of every market every time we invoke _getHypotheticalLiquiditySnapshot.