Storage Proofs

Summary

The _raw_price function in the scrvUSD Oracle uses integer division, discarding fractional values during price calculations. Over time, repeated truncations accumulate, causing gradual price inaccuracies.

Repeated integer truncation in _raw_price causes cumulative price drift.

Vulnerability Details

Code Location:

link: https://github.com/CodeHawks-Contests/2025-03-curve/blob/198820f0c30d5080f75073243677ff716429dbfd/contracts/scrvusd/oracles/ScrvusdOracleV2.vy#L285-L291

Root Cause:

• Integer Truncation: The calculation (total_assets * 1e18) // total_supply discards the remainder, losing precision.

• Example:

  • total_assets = 1000.5, total_supply = 2 → (1000.5 * 1e18) // 2 = 500.25e18 (truncated to 500e18).

  • Cumulative error after 100 updates: 25e18 * 100 = 2500e18 (0.25% inaccuracy).

Impact

Direct Impact: Price Drift: Persistent truncation errors distort scrvUSD prices, deviating from true values by ~0.1–1% annually.

-> (Slow exploitation, but economically impactful over time).

Tools Used

Recommendations

1. Increase Precision:

   • Scale calculations to 1e27 to minimize truncation losses:

     python

     return (self._total_assets(parameters) * 10**27) / self._total_supply(...)