CVE-2018-12025: The transferFrom function of a smart contract implementation for FuturXE (FXE), an Ethereum ERC20 token, allows attackers to accomplish an unauthorize...

Description

The transferFrom function of a smart contract implementation for FuturXE (FXE), an Ethereum ERC20 token, allows attackers to accomplish an unauthorized transfer of digital assets because of a logic error. The developer messed up with the boolean judgment - if the input value is smaller than or equal to allowed value, the transfer session would stop execution by returning false. This makes no sense, because the transferFrom() function should require the transferring value to not exceed the allowed value in the first place. Suppose this function asks for the allowed value to be smaller than the input. Then, the attacker could easily ignore the allowance: after this condition, the `allowed[from][msg.sender] -= value;` would cause an underflow because the allowed part is smaller than the value. The attacker could transfer any amount of FuturXe tokens of any accounts to an appointed account (the `_to` address) because the allowed value is initialized to 0, and the attacker could bypass this restriction even without the victim's private key.

Metrics

EPSS Probability

1.61%

72.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Futurxe	Futurxe	All versions

References

https://medium.com/secbit-media/bugged-smart-contract-f-e-how-could-someone-mess-up-with-boolean-d2251defd6ffThird Party Advisory
https://medium.com/secbit-media/bugged-smart-contract-f-e-how-could-someone-mess-up-with-boolean-d2251defd6ffThird Party Advisory

Timeline

Published: Jun 11, 2018
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-12025?

The transferFrom function of a smart contract implementation for FuturXE (FXE), an Ethereum ERC20 token, allows attackers to accomplish an unauthorized transfer of digital assets because of a logic error. The developer messed up with the boolean judgment - if the input value is smaller than or equal to allowed value, the transfer session would stop execution by returning false. This makes no sense, because the transferFrom() function should require the transferring value to not exceed the allowed value in the first place. Suppose this function asks for the allowed value to be smaller than the input. Then, the attacker could easily ignore the allowance: after this condition, the `allowed[from][msg.sender] -= value;` would cause an underflow because the allowed part is smaller than the value. The attacker could transfer any amount of FuturXe tokens of any accounts to an appointed account (the `_to` address) because the allowed value is initialized to 0, and the attacker could bypass this restriction even without the victim's private key.

How severe is CVE-2018-12025?

Severity scoring for CVE-2018-12025 is pending analysis. The EPSS model estimates a 1.61% probability of exploitation in the next 30 days.

How do I fix CVE-2018-12025?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.