#46960 [SC-Insight] trade order sizes are not validated properly

Submitted on Jun 6th 2025 at 18:09:03 UTC by @gln for IOP | Paradex

• Report ID: #46960

• Report Type: Smart Contract

• Report severity: Insight

• Target: https://github.com/tradeparadex/audit-competition-may-2025/tree/main/paraclear

• Impacts:

Description

Brief/Intro

The function settle_trade_v2 does not verify maker_order.size and taker_order.size fields.

Vulnerability Details

Function settle_order_v2 takes a TradeRequestV2 struct as an argument, struct is defined like this:

#[derive(Copy, Drop, Serde, Debug, PartialEq)]
pub struct OrderV2 {
    pub account: ContractAddress,
    pub market: felt252,
    pub side: felt252,
    pub orderType: felt252,
    pub size: felt252,
    pub price: felt252,
    pub signature_timestamp: felt252,
    pub is_reduce_only: bool,
}

#[derive(Copy, Drop, Serde, Debug, PartialEq)]
pub struct TradeRequestV2 {
    pub id: felt252,
    pub size: felt252,
    pub price: felt252,
    pub traded_at: felt252,
    pub maker_order: OrderV2,
    pub taker_order: OrderV2,
}

Let's see at the code of this function from paraclear.cairo:

  fn settle_trade_v2(ref self: ContractState, trade: TradeRequestV2) -> felt252 {
            self._assert_only_executor();

            let is_maker_order_reduce_only = trade.maker_order.is_reduce_only;
            let is_taker_order_reduce_only = trade.taker_order.is_reduce_only;

1)          assert(trade.size.into() > 1_u256, Errors::TRADE_SIZE_TOO_SMALL);
            let traded_at: u64 = trade.traded_at.try_into().unwrap();
            assert(traded_at > 0_u64, Errors::TRADE_TIME_INVALID);
            assert(
                trade.maker_order.market == trade.taker_order.market, Errors::TRADE_MARKET_MISMATCH,
            );
            assert(
                trade.maker_order.account != trade.taker_order.account, Errors::TRADE_SAME_ACCOUNT,
            );
            assert(trade.maker_order.side != trade.taker_order.side, Errors::TRADE_SAME_SIDE);

            let delegate = self.Paraclear_market_delegate.read(trade.maker_order.market);
            if (delegate.is_non_zero()) {
                let res = IParaclearDispatcher { contract_address: delegate }
                    .settle_trade_v2(trade);
                return res;
            }
		...
 }

1. This the only line where trade.size is checked.

Notice that trade.maker_order.size and trade.taker_order.size fields are not checked at all.

Impact Details

Orders with invalid internal size fields might be processed by Paradex. It may introduce inconsistency between UI and smart contract.

Proof of Concept

Proof of Concept

How to reproduce:

To reproduce, we create a malformed trade request with invalid maker_order.size and taker_order.size fields and verify settle_trade_v2() call was successfull.

1. add test to tests/test_paraclear_trades.cairo, see gist link - https://gist.github.com/gln7/fabee7f76d681c64ba5892c168d339c7

2. run test:

$ snforge test test_settle_trade_issue
...
Collected 1 test(s) from paradex_paraclear package
Running 1 test(s) from tests/
XXXXKE settle_trade_v2 result 1