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ChainLink (LINK) Security Audit Report

Here is the report of the ChainLink Token (LINK) security audit performed by the Callisto Network security department in April 2019.

About Callisto Network and the security department

Utilizing Callisto Network capabilities, we have established a free-for-all system of smart-contracts auditing, to this end, Callisto Network has founded the Callisto security department and deploys treasury funds to pay security auditors for auditing smart-contracts, to reduce risk/flaw in smart-contracts and improve the adoption of programmable blockchains for the whole crypto industry.

ChainLink (LINK) Specificities

Deployed at

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ChainLink (LINK) Security Audit Report

1. Summary

ChainLink Token smart contract security audit report performed by Callisto Security Audit Department

Token description

Symbol      : LINK
Name        : ChainLink Token
Total supply: 1,000,000,000
Decimals    : 18 
Standard    : ERC677

2. In scope

3. Findings

In total, 2 issues were reported including:

  • 2 low severity issues.

No critical security issues were found.

3.1. Known vulnerabilities of ERC-20 token

Severity: low


  1. It is possible to double withdrawal attack. More details here.
  2. Lack of transaction handling mechanism issue. WARNING! This is a very common issue and it already caused millions of dollars losses for lots of token users! More details here.


Add the following code to the transfer(_to address, ...) function:

require( _to != address(this) );

3.2. No zero address checking

Severity: low


In functions transfer(Line 81) and transferFrom(Line 118) there are no zero address checking.

Code snippet

4. Conclusion

The audited smart contract can be deployed. Only low severity issues were found during the audit.

5. Revealing audit reports