From ceabc39304ec298d891d3cde51b8cfddc6842197 Mon Sep 17 00:00:00 2001
From: Sina M <1591639+s1na@users.noreply.github.com>
Date: Mon, 30 Mar 2026 10:01:12 +0200
Subject: [PATCH] internal/ethapi: limit number of calls to eth_simulateV1
 (#34616)

Later on we can consider making these limits configurable if the
use-case arose.
---
 internal/ethapi/api.go      | 10 ++++++++++
 internal/ethapi/simulate.go |  8 ++++++++
 2 files changed, 18 insertions(+)

diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index bb0dd042ab..a62328e201 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -841,6 +841,16 @@ func (api *BlockChainAPI) SimulateV1(ctx context.Context, opts simOpts, blockNrO
 	} else if len(opts.BlockStateCalls) > maxSimulateBlocks {
 		return nil, &clientLimitExceededError{message: "too many blocks"}
 	}
+	var totalCalls int
+	for _, block := range opts.BlockStateCalls {
+		if len(block.Calls) > maxSimulateCallsPerBlock {
+			return nil, &clientLimitExceededError{message: fmt.Sprintf("too many calls in block: %d > %d", len(block.Calls), maxSimulateCallsPerBlock)}
+		}
+		totalCalls += len(block.Calls)
+		if totalCalls > maxSimulateTotalCalls {
+			return nil, &clientLimitExceededError{message: fmt.Sprintf("too many calls: %d > %d", totalCalls, maxSimulateTotalCalls)}
+		}
+	}
 	if blockNrOrHash == nil {
 		n := rpc.BlockNumberOrHashWithNumber(rpc.LatestBlockNumber)
 		blockNrOrHash = &n
diff --git a/internal/ethapi/simulate.go b/internal/ethapi/simulate.go
index aa7609ff93..eacb296132 100644
--- a/internal/ethapi/simulate.go
+++ b/internal/ethapi/simulate.go
@@ -44,6 +44,14 @@ const (
 	// in a single request.
 	maxSimulateBlocks = 256
 
+	// maxSimulateCallsPerBlock is the maximum number of calls allowed in a
+	// single simulated block.
+	maxSimulateCallsPerBlock = 5000
+
+	// maxSimulateTotalCalls is the maximum total number of calls allowed
+	// across all simulated blocks in a single request.
+	maxSimulateTotalCalls = 10000
+
 	// timestampIncrement is the default increment between block timestamps.
 	timestampIncrement = 12
 )