Makina Finance: Permissionless Oracle Update Enables $4.13M Flash Loan Drain

Root Cause

Makina Finance's updateTotalAum() function suffered from three compounding design flaws that together allowed single-transaction oracle manipulation:

1. No access control — the function was external with no role restriction, allowing any caller to trigger an AUM recalculation
2. Synchronous spot-price reads — the function read Curve pool prices atomically within the same block, making it fully exploitable within a flash-loan transaction
3. Pre-approved Weiroll execution paths — included price-sensitive functions with no time delay or sanity-check gate

// CVE-2026-0120 — CRITICAL (CVSS 9.8)
// Ethereum Mainnet, Block 19847623
function updateTotalAum() external {
    // FLAW 1: No access control — any EOA or contract can call
    uint256 totalValue = 0;
    for (uint i = 0; i < positions.length; i++) {
        // FLAW 2: Reads Curve spot price synchronously — same-block manipulation
        totalValue += pool.calc_withdraw_one_coin(positions[i], 0);
    }
    // FLAW 3: No circuit breaker, no TWAP, no sanity check
    totalAum = totalValue;
}

The Cantina CTF audit explicitly excluded the oracle update mechanism from scope; it became the sole exploited surface post-audit.

Attack Steps

MEV note: An MEV searcher decompiled the attack contract in-block, replicated the strategy, and front-ran the original attacker — capturing approximately $4.1M. Makina sent an on-chain message offering a 10% whitehat bounty; the bot operator eventually returned 920.7 ETH, keeping 102.3 ETH.

Impact

• Protocol loss: $4.13M from the DUSD/USDC stablecoin pool
• Net attacker gain: Near-zero after MEV front-run
• Chain: Ethereum Mainnet (Block 19847623, January 20, 2026)
• CVE: CVE-2026-0120 (CVSS 9.8)
• Attack vector: Flash loan oracle manipulation via permissionless price feed

Lessons for Auditors

1. Never exclude oracle update functions from audit scope — even if labeled "administrative," any permissionless function that affects price feeds or AUM is an attack surface.
2. Spot AMM prices ≠ safe oracles — calc_withdraw_one_coin and similar same-block reads from Curve, Uniswap V2, or Balancer pools are trivially manipulable with flash loans; require a TWAP with ≥6 observations and a ≥30-minute window.
3. Restrict every AUM/price-update path — gate behind an authorized keeper role (AccessControl, Ownable) or a decentralized oracle network.
4. Implement circuit breakers — a 10% maximum AUM change per update would have blocked the 165× inflation with zero false positives under normal conditions.
5. Audit scope exclusions are liability — any exclusion touching price-sensitive functions should be escalated to protocol risk, documented publicly, and prioritized in follow-up audits.