Inheritable Smart Contract Wallet

Summary:
The InheritanceManager::_getBeneficiaryIndex function returns zero when a beneficiary address is not found, which is problematic because index 0 is a valid position. This misbehavior may lead to unintended deletions.

Vulnerability Details:
When the beneficiaries array is not empty, a non-existent address will return index 0. This value is then used in InheritanceManager::removeBeneficiary, potentially deleting the wrong beneficiary.

Severity:
High – Incorrect beneficiary removal can lead to loss of funds or mismanagement of estate distributions.

Tools Used:
slither, aderyn, foundry

Recommendations:
Introduce a custom exception (e.g., InheritanceManager__Not_A_Beneficiary()) if the address is not found in the beneficiaries list.