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high Low-Level / Assembly SWC-127 CWE-787

Memory Corruption in Assembly

SAFE-0032 Low-Level / Assembly Checked automatically by the scanner
1

What goes wrong

Assembly writes past allocated memory or mismanages the free-memory pointer (0x40), overwriting adjacent data structures and producing exploitable corruption.

2

How to fix it

the pattern that is safe
assembly {
    let p := mload(0x40)
    mstore(p, val)
    mstore(0x40, add(p, 0x20))   // advance free pointer
}
◆
Respect Solidity memory layout in assembly.
3

Where this has happened

Largest recorded losses in the same failure class — related, not the same bug:

$69.3M · 2023 Curve Finance · Vyper compiler Compiler / toolchain + Reentrancy · 2023
4

Related vulnerabilities in Low-Level / Assembly

SAFE-0117delegatecall to User-Controlled Target critical · Low-Level / Assembly SAFE-0236CREATE2 Address Reuse After selfdestruct (Metamorphic) high · Low-Level / Assembly SAFE-0302delegatecall Inside a Loop high · Low-Level / Assembly SAFE-0031Dirty Higher-Order Bits / Unsafe Assembly Math medium · Low-Level / Assembly SAFE-0088ABI Encoding Collision / Selector Clash medium · Low-Level / Assembly SAFE-0235Inline Assembly Not Marked memory-safe low · Low-Level / Assembly SAFE-0303Inline Assembly return/revert Bypasses Solidity low · Low-Level / Assembly
← PreviousDirty Higher-Order Bits / Unsafe Assembly Math
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