//x/crosschain/keeper/gas_payment.go
func (k Keeper) PayGasInZetaAndUpdateCctx(
	ctx sdk.Context,
	chainID int64,
	cctx *types.CrossChainTx,
	zetaBurnt math.Uint,
	noEthereumTxEvent bool,
) error {
...
// get the gas fee in Zeta using system uniswapv2 pool wzeta/gasZRC20 and adding the protocol fee
//@audit this quote the price of gasZRC20 in zeta denomination. There is no slippage check to ensure `outTxGasFeeInZeta` is not inflated. 
|>	outTxGasFeeInZeta, err := k.fungibleKeeper.QueryUniswapV2RouterGetZetaAmountsIn(ctx, outTxGasFee.BigInt(), gasZRC20)
...
feeInZeta := types.GetProtocolFee().Add(math.NewUintFromBigInt(outTxGasFeeInZeta))
//@audit-info when feeInZeta.GT(zetaBurnt)==true, sender doesn't have enough zeta to pay for gas, this return error, if the cctx is revert tx, this will abort and sender will lose all refunds
	if feeInZeta.GT(zetaBurnt) {
		return cosmoserrors.Wrap(types.ErrNotEnoughZetaBurnt, fmt.Sprintf("feeInZeta(%s) more than zetaBurnt (%s) | Identifiers : %s ",
			feeInZeta,
			zetaBurnt,
			cctx.LogIdentifierForCCTX()),
		)
	}
...
//@audit-info when feeInZeta.GT(zetaBurnt)==false, this substract user zeta balance. Sender might be overcharged for gas due to slippage.
	newAmount := zetaBurnt.Sub(feeInZeta)
...
//@audit This is directly execute the swap based on previous quote amount, slippage will be realized here.
|>	amounts, err := k.fungibleKeeper.CallUniswapV2RouterSwapExactETHForToken(
			ctx,
			types.ModuleAddressEVM,
			types.ModuleAddressEVM,
			outTxGasFeeInZeta,
			gasZRC20,
			noEthereumTxEvent,
		)
...
