Immunefi Audit Competitions
Alchemix V3

58555 sc low alchemistcurator 2 step ownership transfer is implemented incorrectly

Submitted on Nov 3rd 2025 at 07:54:24 UTC by @Oxdeadmanwalking for Audit Comp | Alchemix V3

Description

Brief/Intro

AlchemistCurator implements a 2 step ownership transfer system that allows the current admin to propose a pendingAdmin which can later accept the ownership of the contract by calling acceptAdminOwnership(). This function however is only callable by the current admin so the pending admin will never be able to accept the ownership, leaving room for errors.

Vulnerability Details

AlchemistCurator 2-step ownership transfer system is similar to Ownable2Step by Openzeppelin which aims to minimize the room for error when performing ownership transfering operations.

While other contracts in the system implement the mechanism correctly, in AlchemistCurator , acceptAdminOwnership is only callable by the current admin and not the pending admin breaking the intended design and making the process as error prone as a single step ownership transfer.

    // ===== Admin Management =====
    function transferAdminOwnerShip(address _newAdmin) external onlyAdmin {
        pendingAdmin = _newAdmin;
    }

    // @audit this can never be executed by the pending admin because it is currently not the admin
    function acceptAdminOwnership() external onlyAdmin {
        admin = pendingAdmin;
        pendingAdmin = address(0);
        emit AdminChanged(admin);
    }

acceptAdminOwnership is gated by an onlyAdmin modifier. The only address that can call acceptAdminOwnership is thus, the current admin

Impact Details

The issue essentially breaks the 2-step ownership transfer system leaving the process vulnerable to errors. If the pendingAdmin is set to a wrong address and acceptAdminOwnership is executed then the whole MYT management can break.

References

https://github.com/alchemix-finance/v3-poc/blob/a192ab313c81ba3ab621d9ca1ee000110fbdd1e9/src/AlchemistCurator.sol#L31

Proof of Concept

Proof of Concept

  1. Add this test to AlchemistCurator.t.sol. Import console at the top of the file
import "forge-std/console.sol";

    function test_poc_wrong_2_step_ownership_transfer() public {
        address newAdmin = makeAddr("newAdmin");

        vm.startPrank(admin);
        console.log("Transferring ownership to new admin: ", newAdmin);
        mytCuratorProxy.transferAdminOwnerShip(newAdmin);
        vm.stopPrank();

        console.log("Accepting ownership by new admin: ", newAdmin, "expecting revert...");
        vm.startPrank(newAdmin);
        vm.expectRevert(abi.encode("PD"));
        mytCuratorProxy.acceptAdminOwnership();
        vm.stopPrank();
    }
  1. Observe the logs
[PASS] test_poc_wrong_2_step_ownership_transfer() (gas: 52202)
Logs:
  Transferring ownership to new admin:  0x67ED0Ac45b537A79406E01656d90659325455585
  Accepting ownership by new admin:  0x67ED0Ac45b537A79406E01656d90659325455585 expecting revert...