Rent Collection Exploit Remediation

Overview

Related Detector: Rent Collection Exploit

Incorrect rent handling leads to account deletion. The fix is to always calculate rent-exempt minimums dynamically and verify balances stay above the threshold after any lamport withdrawal.

Recommended Fix

let rent = Rent::get()?;
let min_balance = rent.minimum_balance(account.data_len());
// Before any withdrawal
require!(account.lamports() - amount >= min_balance, BelowRentExempt);

Common Mistakes

Mistake: Hardcoding Rent Values

// WRONG: rent requirements can change
const RENT_EXEMPT: u64 = 890_880;

Always use Rent::get()?.minimum_balance(data_len) for dynamic calculation.

References

• Solana — Rent
• CWE-404: Improper Resource Shutdown or Release