A decentralized autonomous organization (DAO) operates in a blockchain and is governed by voting. Coin voting is the most popular one: a member of a DAO makes a proposal and other coin holders cast their approval with tokens. When the proposal's quorum is reached its script can be executed.
There is a reasonable criticism of such approach which is highlighted by Vitalik Buterin   
- Small groups of wealthy participants («whales») are better at successfully executing decisions than large groups of small-holders.
- Coin voting governance empowers coin holder interests at the expense of other parts of the community.
- Conflicts of interest arise for coin holders who also hold tokens of other DeFi platforms that interact with the platform in question.
- Coin voting's deep fundamental vulnerability to attackers: vote buying   , vote lending  and whales collusion .
- Exposure to complex Game-Theoretic Attacks .
These are non-technical problems. There are also purely technical bugs that a programmer may introduce in the code due to distracted attention or insufficient knowledge of how blockchain works.
There are many DAOs that use coin voting: Aragon-based DAOs, X-DAO, Nexus Mututal, Showball Finance, Pickle Finance, Spirit Swap, Keep3r Network, and many others.
In this article we'll examine technical vulnerabilities that may arise in coin votings and check whether they exist in some of the aforementioned DAOs.