# Attack Vulnerability
*As such, the verification is reliable as long as honest nodes control the network, but is more vulnerable if the network is overpowered by an attacker.*
\- Satoshi Nakamoto, Bitcoin Whitepaper
The reliability of SPV verification hinges on the presence of honest nodes within the network. However, if an **attacker gains control over a significant portion of the network**, the verification process becomes vulnerable. In such cases, the attacker could extend the longest chain of proof-of-work with an invalid block, which may contain invalid transactions or fail to comply with the network's rules.
User wallets, relying on SPV, would be **unable to discern** that the longest chain is not the longest valid chain of proof of work. This situation could allow the attacker to present fabricated information about a transaction, misleading users into believing it has been accepted into the longest chain of proof-of-work.
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