Cancels a consolidation request if the effective balance of the target validator would exceed the max effective balance after processing it, which would result in the excess balance being withdrawn. This is an unintended way to speed up withdrawals when the consolidation queue is faster than the exit queue.
The existing design of consolidation mechanism leaves an opportunity to use consolidation queue for exits which becomes appealing to be abused when there is an imbalance between exit and consolidation queues favoring the latter.
At the date of writing this EIP, the consolidation flaw is being heavily exploited. There are public write ups on how to speed up withdrawals by using this vulnerability.
Even though this is a UX rather than security issue, consolidation queue was never meant to be used for withdrawals, which makes the fix introduced by this EIP an important modification.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 and RFC 8174.
Starting from the beginning of the epoch when this EIP is activated, Consensus Layer client MUST use the modified process_consolidation_request function which code is outlined below.
get_pending_balance_to_consolidateprocess_consolidation_requestNote: This function is extended with the check of the target's balance after consolidation and cancels consolidation request if the balance exceeds the max effective balance.
The new design introduces an iteration over pending consolidations which increases complexity of consolidation processing.
This is done to handle the case when there are multiple consolidations with the same target and each of them doesn't exceed the max effective balance while all of them together do.
This EIP introduces backwards-incompatible changes to the Consensus Layer and must be activated via scheduled network upgrade.
All of the above test cases are implemented here.
When consolidation request results in max effective balance exceeded, it is cancelled on the Consensus Layer, neither request fee nor transaction gas cost are refunded in this case.
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