Crypt::PBKDF2 implementations prior to version 0.261630 generate salts using Perl's built‑in rand function. Because rand is not cryptographically secure, the salts are predictable. This weakness undermines PBKDF2's intended resistance to pre‑computed attacks, allowing an attacker who can observe or guess a salt to greatly reduce the computational effort needed for a brute‑force or dictionary attack.

The vulnerability affects the Crypt::PBKDF2 module distributed by ARODLAND, specifically any installation of version 0.261629 or earlier. The module is used in Perl applications that perform password hashing or key derivation with PBKDF2.

The CVSS score of 7.5 indicates substantial severity, and the EPSS score is not available. The flaw is not listed in KEV, but the use of a predictable random source is a severe weakness. The likely attack vector is any code that imports Crypt::PBKDF2; if an application stores hashed passwords in a database, compromised salts could enable faster cracking. This vulnerability is local to the environment running the module, but once the attacker obtains password hashes, the impact is widespread.