From e408e6cd8f8787cc2b2ae0eb531e0fc604516930 Mon Sep 17 00:00:00 2001
From: sashaodessa <140454972+sashaodessa@users.noreply.github.com>
Date: Thu, 16 Oct 2025 18:16:57 +0200
Subject: [PATCH] Update sync.go

---
 p2p/dnsdisc/sync.go | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/p2p/dnsdisc/sync.go b/p2p/dnsdisc/sync.go
index 073547c90d..2e8b9feb1f 100644
--- a/p2p/dnsdisc/sync.go
+++ b/p2p/dnsdisc/sync.go
@@ -18,7 +18,8 @@ package dnsdisc
 
 import (
 	"context"
-	"math/rand"
+	crand "crypto/rand"
+	"math/big"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common/mclock"
@@ -131,7 +132,12 @@ func (ct *clientTree) syncNextLink(ctx context.Context) error {
 }
 
 func (ct *clientTree) syncNextRandomENR(ctx context.Context) (*enode.Node, error) {
-	index := rand.Intn(len(ct.enrs.missing))
+	// Use CSPRNG to avoid deterministic selection across processes.
+	n, err := crand.Int(crand.Reader, big.NewInt(int64(len(ct.enrs.missing))))
+	if err != nil {
+		return nil, err
+	}
+	index := int(n.Int64())
 	hash := ct.enrs.missing[index]
 	e, err := ct.enrs.resolveNext(ctx, hash)
 	if err != nil {