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fix: reject bids with invalid prev_randao during gossip validation #9533

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Merged
nflaig merged 2 commits into from
Jun 22, 2026
Merged

fix: reject bids with invalid prev_randao during gossip validation #9533

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87cf99d
fix: reject bids with invalid prev_randao during gossip validation
nflaig Jun 19, 2026
7f1c555
Merge branch 'unstable' into nflaig/reject-bids-invalid-prev-randao
nflaig Jun 20, 2026
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7 changes: 7 additions & 0 deletions packages/beacon-node/src/chain/errors/executionPayloadBid.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ export enum ExecutionPayloadBidErrorCode {
UNKNOWN_PARENT_BLOCK_HASH = "EXECUTION_PAYLOAD_BID_ERROR_UNKNOWN_PARENT_BLOCK_HASH",
INVALID_SLOT = "EXECUTION_PAYLOAD_BID_ERROR_INVALID_SLOT",
NOT_LATER_THAN_PARENT = "EXECUTION_PAYLOAD_BID_ERROR_NOT_LATER_THAN_PARENT",
INVALID_PREV_RANDAO = "EXECUTION_PAYLOAD_BID_ERROR_INVALID_PREV_RANDAO",
INVALID_SIGNATURE = "EXECUTION_PAYLOAD_BID_ERROR_INVALID_SIGNATURE",
NO_MATCHING_PROPOSER_PREFERENCES = "EXECUTION_PAYLOAD_BID_ERROR_NO_MATCHING_PROPOSER_PREFERENCES",
PROPOSER_PREFERENCES_FEE_RECIPIENT_MISMATCH = "EXECUTION_PAYLOAD_BID_ERROR_PROPOSER_PREFERENCES_FEE_RECIPIENT_MISMATCH",
Expand Down Expand Up @@ -43,6 +44,12 @@ export type ExecutionPayloadBidErrorType =
| {code: ExecutionPayloadBidErrorCode.UNKNOWN_PARENT_BLOCK_HASH; parentBlockHash: RootHex}
| {code: ExecutionPayloadBidErrorCode.INVALID_SLOT; builderIndex: BuilderIndex; slot: Slot}
| {code: ExecutionPayloadBidErrorCode.NOT_LATER_THAN_PARENT; parentSlot: Slot; slot: Slot}
| {
code: ExecutionPayloadBidErrorCode.INVALID_PREV_RANDAO;
builderIndex: BuilderIndex;
bidPrevRandao: string;
expectedPrevRandao: string;
}
| {code: ExecutionPayloadBidErrorCode.INVALID_SIGNATURE; builderIndex: BuilderIndex; slot: Slot}
| {
code: ExecutionPayloadBidErrorCode.NO_MATCHING_PROPOSER_PREFERENCES;
Expand Down
12 changes: 12 additions & 0 deletions packages/beacon-node/src/chain/validation/executionPayloadBid.ts
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Expand Up @@ -232,6 +232,18 @@ async function validateExecutionPayloadBid(
});
}

// [REJECT] `bid.prev_randao` is the correct RANDAO mix -- i.e. validate that
// `bid.prev_randao == get_randao_mix(parent_state, get_current_epoch(parent_state))`.
const randaoMix = state.getRandaoMix(computeEpochAtSlot(state.slot));
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if (!byteArrayEquals(bid.prevRandao, randaoMix)) {
throw new ExecutionPayloadBidError(GossipAction.REJECT, {
code: ExecutionPayloadBidErrorCode.INVALID_PREV_RANDAO,
builderIndex: bid.builderIndex,
bidPrevRandao: toHex(bid.prevRandao),
expectedPrevRandao: toHex(randaoMix),
});
}

// [REJECT] `signed_execution_payload_bid.signature` is valid with respect to the `bid.builder_index`.
const signatureSet = createSingleSignatureSetFromComponents(
PublicKey.fromBytes(builder.pubkey),
Expand Down
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