diff --git a/modules/network/keeper/msg_server.go b/modules/network/keeper/msg_server.go
index a33237ce..3faee4aa 100644
--- a/modules/network/keeper/msg_server.go
+++ b/modules/network/keeper/msg_server.go
@@ -51,8 +51,29 @@ func (k msgServer) Attest(goCtx context.Context, msg *types.MsgAttest) (*types.M
 		return nil, sdkerr.Wrapf(sdkerrors.ErrNotFound, "validator index not found for %s", msg.ConsensusAddress)
 	}
 
-	// todo (Alex): we need to set a limit to not have validators attest old blocks. Also make sure that this relates with
-	// the retention period for pruning
+	// Enforce attestation height upper bound to prevent storage exhaustion
+	// from future-height spam.
+	currentHeight := ctx.BlockHeight()
+	maxFutureHeight := currentHeight + 1
+	if msg.Height > maxFutureHeight {
+		return nil, sdkerr.Wrapf(sdkerrors.ErrInvalidRequest, "attestation height %d exceeds max allowed height %d", msg.Height, maxFutureHeight)
+	}
+
+	// Enforce attestation height lower bound: reject heights that fall below
+	// the PruneAfter retention window. Attesting pruned/about-to-be-pruned
+	// heights wastes storage and serves no purpose. This uses the same epoch
+	// calculation as PruneOldBitmaps so the two stay aligned.
+	params := k.GetParams(ctx)
+	minHeight := int64(1)
+	if params.PruneAfter > 0 && params.EpochLength > 0 {
+		currentEpoch := uint64(currentHeight) / params.EpochLength
+		if currentEpoch > params.PruneAfter {
+			minHeight = int64((currentEpoch - params.PruneAfter) * params.EpochLength)
+		}
+	}
+	if msg.Height < minHeight {
+		return nil, sdkerr.Wrapf(sdkerrors.ErrInvalidRequest, "attestation height %d is below retention window (min %d)", msg.Height, minHeight)
+	}
 	bitmap, err := k.GetAttestationBitmap(ctx, msg.Height)
 	if err != nil && !errors.Is(err, collections.ErrNotFound) {
 		return nil, sdkerr.Wrap(err, "get attestation bitmap")
diff --git a/modules/network/keeper/msg_server_test.go b/modules/network/keeper/msg_server_test.go
index d7a9cd6c..4b9623ad 100644
--- a/modules/network/keeper/msg_server_test.go
+++ b/modules/network/keeper/msg_server_test.go
@@ -225,6 +225,95 @@ func TestAttestVotePayloadValidation(t *testing.T) {
 	}
 }
 
+func TestAttestHeightBounds(t *testing.T) {
+	myValAddr := sdk.ValAddress("validator1")
+	// With DefaultParams: EpochLength=1, PruneAfter=15
+	// At blockHeight=100: currentEpoch=100, minHeight=(100-7)*1=93
+
+	specs := map[string]struct {
+		blockHeight int64
+		attestH     int64
+		expErr      error
+	}{
+		"future height rejected": {
+			blockHeight: 100,
+			attestH:     200,
+			expErr:      sdkerrors.ErrInvalidRequest,
+		},
+		"two-ahead rejected": {
+			blockHeight: 100,
+			attestH:     102,
+			expErr:      sdkerrors.ErrInvalidRequest,
+		},
+		"current height accepted": {
+			blockHeight: 100,
+			attestH:     100,
+		},
+		"next height accepted": {
+			blockHeight: 100,
+			attestH:     101,
+		},
+		"stale height rejected": {
+			blockHeight: 100,
+			attestH:     1,
+			expErr:      sdkerrors.ErrInvalidRequest,
+		},
+		"below retention window rejected": {
+			blockHeight: 100,
+			attestH:     84, // minHeight = 85
+			expErr:      sdkerrors.ErrInvalidRequest,
+		},
+		"at retention boundary accepted": {
+			blockHeight: 100,
+			attestH:     93, // exactly minHeight
+		},
+		"early chain no stale rejection": {
+			blockHeight: 16,
+			attestH:     1,
+		},
+	}
+
+	for name, spec := range specs {
+		t.Run(name, func(t *testing.T) {
+			sk := NewMockStakingKeeper()
+			cdc := moduletestutil.MakeTestEncodingConfig().Codec
+			keys := storetypes.NewKVStoreKeys(types.StoreKey)
+			logger := log.NewTestLogger(t)
+			cms := integration.CreateMultiStore(keys, logger)
+			authority := authtypes.NewModuleAddress("gov")
+			keeper := NewKeeper(cdc, runtime.NewKVStoreService(keys[types.StoreKey]), sk, nil, nil, authority.String())
+			server := msgServer{Keeper: keeper}
+			ctx := sdk.NewContext(cms, cmtproto.Header{
+				ChainID: "test-chain",
+				Time:    time.Now().UTC(),
+				Height:  spec.blockHeight,
+			}, false, logger).WithContext(t.Context())
+
+			require.NoError(t, keeper.SetParams(ctx, types.DefaultParams()))
+
+			// Setup: add attester and build index map
+			require.NoError(t, keeper.SetAttesterSetMember(ctx, myValAddr.String()))
+			require.NoError(t, keeper.BuildValidatorIndexMap(ctx))
+
+			msg := &types.MsgAttest{
+				Authority:        myValAddr.String(),
+				ConsensusAddress: myValAddr.String(),
+				Height:           spec.attestH,
+				Vote:             make([]byte, MinVoteLen),
+			}
+
+			rsp, err := server.Attest(ctx, msg)
+			if spec.expErr != nil {
+				require.ErrorIs(t, err, spec.expErr)
+				require.Nil(t, rsp)
+				return
+			}
+			require.NoError(t, err)
+			require.NotNil(t, rsp)
+		})
+	}
+}
+
 var _ types.StakingKeeper = &MockStakingKeeper{}
 
 type MockStakingKeeper struct {
diff --git a/modules/network/types/params.go b/modules/network/types/params.go
index 811bf9e2..d97a34d7 100644
--- a/modules/network/types/params.go
+++ b/modules/network/types/params.go
@@ -11,7 +11,7 @@ var (
 	DefaultEpochLength      = uint64(1)                         // Changed from 10 to 1 to allow attestations on every block
 	DefaultQuorumFraction   = math.LegacyNewDecWithPrec(667, 3) // 2/3
 	DefaultMinParticipation = math.LegacyNewDecWithPrec(5, 1)   // 1/2
-	DefaultPruneAfter       = uint64(7)
+	DefaultPruneAfter       = uint64(15)                        // also used as number of blocks for attestations to land
 	DefaultSignMode         = SignMode_SIGN_MODE_CHECKPOINT
 )