Immunefi Audit Competitions
Alchemix V3

#57394 [SC-Low] `acceptAdminOwnership()` only allows the current admin to finalise transfers

Submitted on Oct 25th 2025 at 19:48:50 UTC by @pxng0lin for Audit Comp | Alchemix V3

Description

Bug Description

AlchemistCurator.acceptAdminOwnership() @src/AlchemistCurator.sol#31-34 is guarded by onlyAdmin. After transferAdminOwnerShip() sets pendingAdmin, the same admin must also call acceptAdminOwnership() because any other address fails the modifier check. A nominated pendingAdmin cannot execute the function, so the contract relies on the outgoing admin to complete both steps of the handover. If that account becomes unavailable, the transition cannot finish.

Impact

  • Admin handover dependency: The nominated address cannot finalise control; only the existing admin can call the second step.
  • Operational risk: If the current admin loses access after scheduling a transfer, the contract remains under the old admin indefinitely.

Risk Breakdown

  • Privilege required: Current admin.
  • Likelihood: Medium

Recommendation

Allow the nominated party to accept by checking msg.sender == pendingAdmin (e.g., an onlyPendingAdmin modifier) before updating admin.

References

  • Handover initiation: transferAdminOwnerShip() @src/AlchemistCurator.sol#26-29.
  • Acceptance function: acceptAdminOwnership() @src/AlchemistCurator.sol#31-34.

Proof of Concept

Proof of Concept

  1. Existing ownership: The contract is deployed with admin = addrA.
  2. Planned handover: addrA initiates the transition by calling transferAdminOwnerShip(addrB). Storage now records pendingAdmin = addrB.
  3. New admin tries to accept: Acting as addrB, we call acceptAdminOwnership(). The call reverts with Unauthorized("PD") because onlyAdmin accepts only the current admin.
  4. Original admin finalises instead: addrA repeats the call and succeeds. The function assigns admin = addrB and clears pendingAdmin, even though addrB never interacted.
  5. Failure mode: If addrA disappears between steps 2 and 4—lost keys, compromised wallet—the takeover cannot complete. Governance stays bound to addrA.