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high Logic / State No SWC entry CWE-837

Missing Claimed Flag — Double Claim

SAFE-0249 Logic / State Checked automatically by the scanner
1

What goes wrong

A claim/withdraw/redeem does not record that the caller (or the id) has already claimed. The same entitlement is claimed repeatedly until the contract is drained.

2

The vulnerable pattern

proof of concept — how it is exploited
// claim() pays amount but never sets a flag.
// attacker calls claim() in a loop -> drains the distribution.
3

How to fix it

the pattern that is safe
require(!claimed[msg.sender], "already claimed");
claimed[msg.sender] = true;
_payout(msg.sender, amount);
◆
Record and check a claimed flag before paying out.
4

Where this has happened

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

$586M · 2022 BNB Chain Token Hub Input validation · 2022 $326M · 2022 Wormhole Input validation · 2022 $197M · 2023 Euler Finance Input validation · 2023 $190M · 2022 Nomad Bridge Input validation · 2022
5

Related vulnerabilities in Logic / State

SAFE-0071Incorrect Accounting / Internal Balance Drift high · Logic / State SAFE-0095Uninitialized Storage Pointer (legacy) high · Logic / State SAFE-0146msg.value Reused Across a Loop / Multicall high · Logic / State SAFE-0070State Desync Between Related Variables medium · Logic / State SAFE-0081Storage vs Memory Misuse Causing State Bug medium · Logic / State SAFE-0093Selfdestruct Dependency / Forced Removal Assumption medium · Logic / State SAFE-0094Predictable Contract Address / CREATE2 Reorg Risk medium · Logic / State SAFE-0142Uninitialised Storage Pointer medium · Logic / State
← PreviousCross-Chain Message Ordering Not Enforced
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