the main problem for Bitcoin Unlimited, as pointed out by information security expert Andreas Antonopoulos, is that it lacks a significant development community to perform proper quality analysis. The number of developers working on Bitcoin Unlimited and Bitcoin Classic is relatively small, and the code that included the exploited vulnerability was merged after being reviewed by only one person — not a lot for security-critical code protecting people’s money

the vulnerabilities are so glaringly obvious, it is clear no one has audited their code because these stick out like a sore thumb,” she said. “I’m astounded the mining industry are running this software. But since they are, and a lot of people could get harmed, the best I can do, other than recommending they don’t use Bitcoin Unlimited, is to disclose the issues and hope they are competent enough to fix it.”