MEV Vulnerabilities Remediation

Overview

Related Detector: MEV Vulnerabilities

MEV attacks exploit programs that perform state-dependent value transfers without protective bounds. The primary fix is to require user-supplied slippage parameters (minimum output amounts) and execution deadlines on every value-transferring operation. Combined with atomic execution patterns, these defenses make sandwich attacks unprofitable.

Recommended Fix

Before (Vulnerable)

use anchor_lang::prelude::*;

// Vulnerable: no slippage or deadline protection
pub fn execute_swap(ctx: Context<Swap>, amount: u64) -> Result<()> {
    let price = get_current_price(&ctx.accounts.pool)?;
    let output = calculate_output(amount, price);
    transfer_tokens(&ctx, output)?;
    Ok(())
}

After (Fixed)

use anchor_lang::prelude::*;

// Fixed: user-supplied minimum output and deadline
pub fn execute_swap(
    ctx: Context<Swap>,
    amount: u64,
    min_output: u64,
    deadline: i64,
) -> Result<()> {
    let clock = Clock::get()?;
    require!(clock.unix_timestamp <= deadline, SwapError::DeadlineExceeded);

    let price = get_current_price(&ctx.accounts.pool)?;
    let output = calculate_output(amount, price);
    require!(output >= min_output, SwapError::SlippageExceeded);

    transfer_tokens(&ctx, output)?;
    Ok(())
}

Alternative Mitigations

Commit-Reveal Schemes

For operations where slippage bounds alone are insufficient, implement a two-phase commit-reveal pattern. Users commit a hashed intention in one transaction and reveal it in a later slot, preventing validators from frontrunning the actual operation.

Use Jito Bundles

Jito’s bundle mechanism allows users to submit multiple transactions atomically, reducing the window for sandwich attacks. While this is an infrastructure-level mitigation, programs should still enforce on-chain slippage bounds.

Common Mistakes

Mistake: Hardcoded Slippage Tolerance

// WRONG: hardcoded 5% slippage -- too permissive for large trades
let min_output = expected_output * 95 / 100;

Always accept the minimum output as a user-supplied parameter so traders can set appropriate bounds for their trade size.

Mistake: Missing Deadline

// WRONG: slippage check without deadline
require!(output >= min_output, SwapError::SlippageExceeded);
// Transaction could sit in mempool and execute much later at an unfavorable price

Always pair slippage checks with an expiration timestamp.

References

• Solana — Transactions
• CWE-362: Concurrent Execution Using Shared Resource
• Jito MEV Documentation