This paper studies the security of Ring Oscillator Physically Unclonable Function (PUF) with Enhanced Challenge-Response Pairs as proposed by Delavar et al. We present an attack that can predict all PUF responses after querying the PUF with $$n+2$$n+2 attacker-chosen queries. This result renders the proposed RO-PUF with Enhanced Challenge-Response Pairs inapt for most typical PUF use cases, including but not limited to all cases where an attacker has query access.