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# Tutorial 3: Approvals and Safe Approvals

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[**Book an audit with Zokyo**](https://www.zokyo.io/)
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**ERC20 Approval Vulnerabilities & Mitigating with OpenZeppelin's Safe Approvals:** An Auditor's Guide. This comprehensive tutorial is tailored for blockchain auditors and newcomers, providing them with the essential tools to identify and rectify approval-related vulnerabilities in ERC20 token-based smart contracts. Leveraging real-world examples and effective strategies, the tutorial serves as an in-depth resource for understanding, detecting, and tackling these often underappreciated yet potentially critical security flaws.
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ERC20 tokens, the standard for fungible tokens on the Ethereum network, have become the pillars of numerous DeFi applications. However, beneath the vast array of operations they facilitate, there's a critical function - 'approval' - that is often the source of substantial vulnerabilities when mismanaged.

Such vulnerabilities are not mere theoretical constructs, but have been unearthed during smart contract audits and exposed in bug bounties, leading to significant security breaches. These incidents underscore the importance of securing the 'approval' function to protect assets and maintain the integrity of contracts.

In this tutorial, we will dissect these approval-related vulnerabilities, drawing upon real-world examples from audit reports and bug bounties to illustrate their potential impact. We will delve into OpenZeppelin's safe approvals, a widely-used library offering robust mitigation techniques. Yet, as with all tools, correct implementation is key - a point we'll stress as we explore the consequences of incorrect usage.


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