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Fail authentication when the password or an authentication key contains a null byte, before any database lookup or BCrypt call.
simi
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October 12, 2026 13:46
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Security scanners often send a null byte in login fields and report the resulting error as a security issue. In Devise this can raise
ArgumentErrorin BCrypt, including the dummy hash in paranoid mode, and PostgreSQL rejects null bytes in the user lookup.This rejects null bytes in the password and authentication keys early, as a normal failed login. Rejecting them at the input boundary is common practice. Django does it for all form fields (ticket #28201), and PHP's fix for CVE-2024-3096 recommends the same.