Submission Details
Severity:
Commitment hash is malleable
Summary
Use of abi.enocdePacked is risky since it can cause hash collision.
keccak256(abi.encodePacked(move, _salt));
Vulnerability Details
We are packing the values tightly, which means different combinations of move and salt** can result in the same byte stream**, leading to hash collisions if the types aren’t fixed length.
Impact
abi.encodePacked(uint8(1), "23") == 0x0132
abi.encodePacked(uint8(18), "3") == 0x123
Hex 0x0132 == 0x123
Tools Used
Forge
Recommendations
Use abi.enocde instead of abi.enocdePacked
Rewards breakdown
nSLOC
349This contest has a flat reward structure with the following payouts:
100 EXP
20 EXP
2 EXP
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