Demo Report

Smart Contract Security Audit Report

Uniswap V2 — Partial Review

Version 1.0•November 2025•Aegis Labs

1. Overview

This report presents the findings of a security audit conducted by Aegis Labs on a subset of the Uniswap V2 core contracts, specifically the Pair and Router implementations.

The audit focused on cross-chain message handling, reentrancy vectors, liquidity invariants, and upgradeability risks. Automated analysis was supplemented with manual code review.

2. Scope

In Scope

  • UniswapV2Pair.sol
  • UniswapV2Router02.sol
  • swap / addLiquidity / removeLiquidity flows

Out of Scope

  • Factory contracts
  • ERC20 token implementations
  • Oracle / TWAP logic

3. Methodology

1

Static Analysis

Slither, Mythril for automated vulnerability detection

2

Manual Review

Line-by-line audit of business logic and edge cases

3

Cross-chain Focus

Message verification, replay protection, invariant checks

4. Risk Rating

Critical
0
High
1
Medium
3
Low
1
Info
0

Overall Assessment: 1 High and 3 Medium severity issues identified. No Critical findings. Recommendations provided for all items.

5. Findings

Detailed vulnerability list with descriptions, recommendations, and code references.

H-01Reentrancy in swap via callbackHighM-01Flash loan arbitrage via sync manipulationMediumM-02Rounding bias in getAmountOutMediumM-03Missing zero-address check in RouterMediumL-01Unchecked return value for non-standard ERC20Low
H-01High

Reentrancy in swap via callback

Description

The swap function triggers a callback to the recipient before state updates complete. A malicious pair contract or receiver can re-enter and drain liquidity during the callback window.

Recommendation

Apply checks-effects-interactions pattern. Update all state (balances, reserves) before performing the callback. Consider ReentrancyGuard as defense-in-depth.

Code Reference

function swap(uint amount0Out, uint amount1Out, address to, bytes data) external {
    // ... checks ...
    if (amount0Out > 0) _safeTransfer(_token0, to, amount0Out);
    if (amount1Out > 0) _safeTransfer(_token1, to, amount1Out);
    if (data.length > 0) IUniswapV2Callee(to).uniswapV2Call(...);  // Re-entry point
    _update(balance0, balance1, ...);  // State update too late
}
M-01Medium

Flash loan arbitrage via sync manipulation

Description

An attacker can flash loan, call sync() to skew reserves, execute arbitrage, and repay within the same transaction. Enables low-cost MEV extraction.

Recommendation

Document sync() behavior. Consider time-weighted oracles for dependent protocols. Informational for integrators.

M-02Medium

Rounding bias in getAmountOut

Integer division can favor the pool in edge cases. Document rounding behavior; use getAmountIn or safety margins for exact-amount protocols.

M-03Medium

Missing zero-address check in Router

addLiquidity does not reject tokenA == tokenB or address(0). Add explicit validation at Router entry points.

L-01Low

Unchecked return value for non-standard ERC20

Some tokens do not return bool. Use SafeERC20 or check return values where applicable.

This is what you get

Structured, actionable reports. Not PDFs—living documents you can share and reference.

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