Executive brief
The Crypt::PBKDF2 Perl library, used for securely storing passwords, was found to use outdated default settings that make it easier for attackers to crack passwords. By using a weak hashing algorithm and a low number of repetitions (iterations), the library produced hashes that could be bypassed much faster than modern security standards allow. If an attacker gains access to a database of these hashes, they could more easily recover original user passwords, leading to unauthorized account access.
Technical details
Crypt::PBKDF2 prior to version 0.261630 defaults to HMAC-SHA1 with only 1,000 iterations. Modern security standards, such as those from OWASP, recommend at least 210,000 to 600,000 iterations depending on the hash function to provide adequate resistance against GPU-accelerated brute-force attacks. An attacker with access to the hashed password data (e.g., via SQL injection or database leak) can perform offline cracking significantly faster than if the library used modern defaults. The vulnerability is addressed in version 0.261630, which updates the default to HMAC-SHA256 and 600,000 iterations.
Affected products
- Perl CPAN Crypt::PBKDF2 before 0.261630
Timeline
- 2026-06-11: patched: Version 0.261630 released with updated defaults.
- 2026-06-12: disclosed: CVE-2026-9641 published.