What issue is associated with short ASCII passphrases in WPA/WPA2-Personal networks?

Short ASCII passphrases in WPA/WPA2-Personal networks are more susceptible to dictionary attacks than longer passphrases due to their limited variation and predictability. Dictionary attacks leverage a precompiled list of common passwords or phrases to efficiently guess the passphrase used to secure the network. When a passphrase is shorter, it typically reduces the potential combination of characters, making it easier for attackers to use these lists to crack passwords.

Longer and more complex passphrases increase the difficulty of such attacks since they exponentially increase the total number of possible combinations. Additionally, if the passphrase is constructed using common words or phrases, it becomes even more vulnerable, as attackers can prioritize these in their dictionaries. Thus, the shorter the passphrase, the greater the risk of successful attacks, making this a critical consideration for securing a wireless network.