MEDIUM severity: BaseAsyncSwap Operation Is Unclear. The BaseAsyncSwap hook skips normal swap logic for exact-input swaps by minting ERC-6909 claim tokens to itself, but it does not specify how these tokens should be handled. There is no mechanism to track which user or pool the tokens belong to, nor any logic for distributing or refunding them.

The...

Vulnerable code:
// SPDX-License-Identifier: MIT
// OpenZeppelin Uniswap Hooks (last updated v0.1.0) (src/base/BaseAsyncSwap.sol)

pragma solidity ^0.8.24;

import {BaseHook} from "src/base/BaseHook.sol";
import {Hooks} from "v4-core/src/libraries/Hooks.sol";
import {PoolKey} from "v4-core/src/types/PoolKey.sol";
import {IPoolManager} from "v4-core/src/interfaces/IPoolManager.sol";
import {BeforeSwapDelta, BeforeSwapDeltaLibrary, toBeforeSwapDelta} from "v4-core/src/types/BeforeSwapDelta.sol";
import {Currency} from "v4-core/src/types/Currency.sol";
import {SafeCast} from "v4-core/src/libraries/SafeCast.sol";
import {CurrencySettler} from "src/utils/CurrencySettler.sol";

/**
 * @dev Base implementation for async swaps, which skip the v3-like swap implementation of the `PoolManager`
 * by taking the full swap input amount and returning a delta that nets out the specified amount to 0.
 *
 * This base hook allows developers to implement arbitrary logic to handle swaps, including use-cases like
 * asynchronous swaps and custom swap-ordering. However, given this flexibility, developers should ensure
 * that any logic implemented interacts safely with the `PoolManager` and works correctly.
 *
 * In order to handle async swaps, the hook mints ERC-6909 claim tokens for the specified currency and amount.
 * Inheriting contracts are free to handle these claim tokens as necessary, which can be redeemed for the
 * underlying currency by using the `settle` function from the `CurrencySettler` library.
 *
 * IMPORTANT: If the hook is used for multiple pools, the ERC-6909 tokens must be separated and managed
 * independently for each pool in order to prevent draining of ERC-6909 tokens from one pool to another.
 *
 * NOTE: The hook only supports async exact-input swaps. Exact-output swaps will be processed normally
 * by the `PoolManager`.
 *
 * WARNING: This is experimental software and is provided on an "as is" and "as available" basis. We do
 * not give any warranties and will not be liable for any losses incurred through any use of this code
 * base.
 *
 * _Available since v0.1.0_
 */
abstract contract BaseAsyncSwap is BaseHook {
    using SafeCast for uint256;
    using CurrencySettler for Currency;

    /**
     * @dev Set the `PoolManager` address.
     */
    constructor(IPoolManager _poolManager) BaseHook(_poolManager) {}

    /**
     * @dev Skip the v3-like swap implementation of the `PoolManager` by returning a delta that nets out the
     * specified amount to 0 to enable asynchronous swaps.
     */
    function _beforeSwap(address, PoolKey calldata key, IPoolManager.SwapParams calldata params, bytes calldata)
        internal
        virtual
        override
        returns (bytes4, BeforeSwapDelta, uint24)
    {
        // Async swaps are only possible on exact-input swaps, so exact-output swaps are executed by the `PoolManager` as normal
        if (params.amountSpecified < 0) {
            // Determine which currency is specified
            Currency specified = params.zeroForOne ? key.currency0 : key.currency1;

            // Get the positive specified amount
            uint256 specifiedAmount = uint256(-params.amountSpecified);

            // Mint ERC-6909 claim token for the specified currency and amount
            specified.take(poolManager, address(this), specifiedAmount, true);

            // Return delta that nets out specified amount to 0.
            return (this.beforeSwap.selector, toBeforeSwapDelta(specifiedAmount.toInt128(), 0), 0);
        } else {
            return (this.beforeSwap.selector, BeforeSwapDeltaLibrary.ZERO_DELTA, 0);
        }
    }

    /**
     * @dev Set the hook permissions, specifically `beforeSwap` and `beforeSwapReturnDelta`.
     *
     * @return permissions The hook permissions.
     */
    function getHookPermissions() public pure virtual override returns (Hooks.Permissions memory permissions) {
        return Hooks.Permissions({
            beforeInitialize: false,
            afterInitialize: false,
            beforeAddLiquidity: false,
            beforeRemoveLiquidity: false,
            afterAddLiquidity: false,
            afterRemoveLiquidity: false,
            beforeSwap: true,
            afterSwap: false,
            beforeDonate: false,
            afterDonate: false,
            beforeSwapReturnDelta: true,
            afterSwapReturnDelta: false,
            afterAddLiquidityReturnDelta: false,
            afterRemoveLiquidityReturnDelta: false
        });
    }
}


Vulnerability type: CWE-691|CWE-841