diff --git a/beacon-chain/sync/validate_blob.go b/beacon-chain/sync/validate_blob.go
index 5e50d8bda2a6..428f084e7e71 100644
--- a/beacon-chain/sync/validate_blob.go
+++ b/beacon-chain/sync/validate_blob.go
@@ -12,6 +12,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/signing"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/transition"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
+	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
 	"github.com/prysmaticlabs/prysm/v4/config/params"
 	"github.com/prysmaticlabs/prysm/v4/crypto/bls"
 	"github.com/prysmaticlabs/prysm/v4/crypto/rand"
@@ -61,10 +62,16 @@ func (s *Service) validateBlob(ctx context.Context, pid peer.ID, msg *pubsub.Mes
 	}
 	blob := sBlob.Message
 
+	// [REJECT] The sidecar's index is consistent with `MAX_BLOBS_PER_BLOCK` -- i.e. `sidecar.index < MAX_BLOBS_PER_BLOCK`
+	if blob.Index >= fieldparams.MaxBlobsPerBlock {
+		log.WithFields(blobFields(blob)).Debug("Sidecar index > MAX_BLOBS_PER_BLOCK")
+		return pubsub.ValidationReject, errors.New("incorrect blob sidecar index")
+	}
+
 	// [REJECT] The sidecar is for the correct subnet -- i.e. compute_subnet_for_blob_sidecar(sidecar.index) == subnet_id.
 	want := fmt.Sprintf("blob_sidecar_%d", computeSubnetForBlobSidecar(blob.Index))
 	if !strings.Contains(*msg.Topic, want) {
-		log.WithFields(blobFields(blob)).Debug("Sidecar blob does not match topic")
+		log.WithFields(blobFields(blob)).Debug("Sidecar index  does not match topic")
 		return pubsub.ValidationReject, fmt.Errorf("wrong topic name: %s", *msg.Topic)
 	}
 
diff --git a/beacon-chain/sync/validate_blob_test.go b/beacon-chain/sync/validate_blob_test.go
index 0a306bb0693b..2ff82f711818 100644
--- a/beacon-chain/sync/validate_blob_test.go
+++ b/beacon-chain/sync/validate_blob_test.go
@@ -19,6 +19,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state/stategen"
 	mockSync "github.com/prysmaticlabs/prysm/v4/beacon-chain/sync/initial-sync/testing"
 	lruwrpr "github.com/prysmaticlabs/prysm/v4/cache/lru"
+	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
 	"github.com/prysmaticlabs/prysm/v4/config/params"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
 	"github.com/prysmaticlabs/prysm/v4/crypto/bls"
@@ -81,6 +82,31 @@ func TestValidateBlob_InvalidMessageType(t *testing.T) {
 	require.Equal(t, result, pubsub.ValidationReject)
 }
 
+func TestValidateBlob_InvalidIndex(t *testing.T) {
+	ctx := context.Background()
+	p := p2ptest.NewTestP2P(t)
+	chainService := &mock.ChainService{Genesis: time.Unix(time.Now().Unix()-int64(params.BeaconConfig().SecondsPerSlot), 0)}
+	s := &Service{cfg: &config{p2p: p, initialSync: &mockSync.Sync{}, clock: startup.NewClock(chainService.Genesis, chainService.ValidatorsRoot)}}
+
+	msg := util.NewBlobsidecar()
+	msg.Message.Index = fieldparams.MaxBlobsPerBlock
+	buf := new(bytes.Buffer)
+	_, err := p.Encoding().EncodeGossip(buf, msg)
+	require.NoError(t, err)
+
+	topic := p2p.GossipTypeMapping[reflect.TypeOf(msg)]
+	digest, err := s.currentForkDigest()
+	require.NoError(t, err)
+	topic = s.addDigestAndIndexToTopic(topic, digest, 1)
+	result, err := s.validateBlob(ctx, "", &pubsub.Message{
+		Message: &pb.Message{
+			Data:  buf.Bytes(),
+			Topic: &topic,
+		}})
+	require.ErrorContains(t, "incorrect blob sidecar index", err)
+	require.Equal(t, result, pubsub.ValidationReject)
+}
+
 func TestValidateBlob_InvalidTopicIndex(t *testing.T) {
 	ctx := context.Background()
 	p := p2ptest.NewTestP2P(t)