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medium External Calls No SWC entry CWE-130

Return Data Length Not Checked (Memory Bomb / Decode Error)

SAFE-0092 External Calls Checked automatically by the scanner
1

What goes wrong

After a low-level call, returndata is decoded or copied without checking its length, enabling a malicious callee to return huge data (gas griefing) or malformed data that mis-decodes.

2

How to fix it

the pattern that is safe
(bool ok, bytes memory d) = t.call(data);
require(ok && d.length >= 32, "bad return");
uint x = abi.decode(d, (uint));
◆
Validate returndata length and bound it.
3

Where this has happened

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

$80M · 2022 Fei Protocol / Rari Capital Fuse Reentrancy · 2022 $69.3M · 2023 Curve Finance · Vyper compiler Compiler / toolchain + Reentrancy · 2023 ~$60M · 2016 The DAO Reentrancy · 2016
4

Related vulnerabilities in External Calls

SAFE-0028Delegatecall to Untrusted / Arbitrary Target critical · External Calls SAFE-0029Arbitrary External Call Injection critical · External Calls SAFE-0026Unchecked Low-Level Call Return Value high · External Calls SAFE-0027Unchecked ERC-20 transfer/transferFrom Return high · External Calls SAFE-0131Unchecked Low-Level Call Return Value high · External Calls SAFE-0310Return Value of send() Ignored high · External Calls SAFE-0125Return-Data Bomb / Gas Griefing on External Call medium · External Calls SAFE-0143transfer()/send() 2300-Gas Stipend medium · External Calls
← PreviousNFT Receiver / onERC721Received Missing Validation
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