From dc3b20747c0495a06c2f39f373c2b06e27f6bcd5 Mon Sep 17 00:00:00 2001
From: Lion - dapplion <35266934+dapplion@users.noreply.github.com>
Date: Thu, 9 Mar 2023 23:02:56 +0800
Subject: [PATCH] Fix domain derivation on LC syncAggregate validation

---
 packages/light-client/src/spec/validateLightClientUpdate.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/light-client/src/spec/validateLightClientUpdate.ts b/packages/light-client/src/spec/validateLightClientUpdate.ts
index 3504773b76ab..785f4242a0af 100644
--- a/packages/light-client/src/spec/validateLightClientUpdate.ts
+++ b/packages/light-client/src/spec/validateLightClientUpdate.ts
@@ -113,7 +113,7 @@ export function validateLightClientUpdate(
 
   const signingRoot = ssz.phase0.SigningData.hashTreeRoot({
     objectRoot: ssz.phase0.BeaconBlockHeader.hashTreeRoot(update.attestedHeader.beacon),
-    domain: store.config.getDomain(update.signatureSlot, DOMAIN_SYNC_COMMITTEE),
+    domain: store.config.getDomain(update.signatureSlot - 1, DOMAIN_SYNC_COMMITTEE),
   });
 
   if (!isValidBlsAggregate(participantPubkeys, signingRoot, update.syncAggregate.syncCommitteeSignature)) {