69794 sc low user cannot revoke migration approval if migrator loses migrator role

Submitted on Mar 16th 2026 at 21:29:50 UTC by @CarlosMB for Audit Comp | Folks Finance: Staking Contracts

• Report ID: #69794

• Report Type: Smart Contract

• Report severity: Low

• Target: https://github.com/Folks-Finance/folks-staking-contracts/blob/main/src/Staking.sol

Description

Intro

The function setMigrationPermit requires the target address to currently have MIGRATOR_ROLE. If the role is revoked from a migrator, users can no longer call setMigrationPermit(migrator, false) to revoke their previously granted approval. This leaves stale migration approvals that users cannot clear themselves.

Vulnerability Details

The function setMigrationPermit performs the following check:

if (!hasRole(MIGRATOR_ROLE, _migrator))
    revert MigratorNotFound(_migrator);

This check is executed regardless of whether the user is granting or revoking permission.

If a migrator previously had MIGRATOR_ROLE and users granted permission via setMigrationPermit(migrator, true);

and the admin later revokes the role: revokeRole(MIGRATOR_ROLE, migrator);

users are unable to revoke the permission because calling setMigrationPermit(migrator, false); will revert due to the role check.

As a result, the contract can contain stale approvals that users cannot clear.

Impact Details

Users cannot revoke migration approvals once a migrator loses MIGRATOR_ROLE, leaving stale permissions stored in migrationPermits.

This does not directly lead to loss of funds because migration requires the caller to have MIGRATOR_ROLE. However, it creates a situation where users cannot clean up previously granted permissions.

Category: Insight → Code Optimizations and Enhancements

Proof of Concept

1. User authorizes a migrator:

   setMigrationPermit(migrator, true);

2. Admin revokes the migrator role:

   revokeRole(MIGRATOR_ROLE, migrator);

3. User attempts to revoke approval:

   setMigrationPermit(migrator, false);

4. Transaction reverts due to:

   if (!hasRole(MIGRATOR_ROLE, _migrator))
       revert MigratorNotFound(_migrator);

Result:

migrationPermits[migrator][user] remains true and cannot be cleared by the user.

Recommendation

Allow users to revoke permissions even if the address no longer has MIGRATOR_ROLE. For example:

if (_isMigrationPermitted && !hasRole(MIGRATOR_ROLE, _migrator))
    revert MigratorNotFound(_migrator);