Catalyst::Plugin::Authentication versions before 0.10029 for Perl allow timing attacks on stored passwords via eq comparisons in the legacy password verifier. CVE-2026-5091 was fixed in the realm-based verifier. The legacy verifier, used by the deprecated login method, compares clear-text passwords, crypt hashes and base64 digests with eq, so the comparison time depends on how many leading bytes match. A remote attacker can use response-time differences to guess the stored password or hash.