CVE-2026-94206: CWE-916 Use of Password Hash With Insufficient Computational Effort in danielberkompas cloak_ecto

The vulnerability arises because the dump/1 callback in Cloak.Ecto.PBKDF2 (and previously in cloak) calls :pbkdf2.pbkdf2/4 with the configured size parameter in place of the iteration count. Although the iterations setting is validated, it is never used in the hash computation. With default settings (iterations: 600,000 and size: 32), the actual number of PBKDF2 rounds performed is only 32 instead of 600,000. This reduces the computational cost of offline guessing attacks by approximately 18,750 times, making brute-force attacks on low-entropy plaintexts like email addresses much more feasible. The affected versions are cloak_ecto from 1.0.0-alpha.0 onward and cloak from 0.7.0 up to but not including 1.0.0-alpha.0.

An attacker who obtains the hashed values and the configured secret can perform offline brute-force attacks on low-entropy plaintexts significantly faster than intended due to the drastically reduced iteration count in the PBKDF2 hashing. This undermines the security guarantees of the password hashing mechanism, increasing the risk of credential compromise or data exposure.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, users should be aware of the reduced computational effort in the hashing process and consider additional protective measures such as increasing the entropy of plaintext inputs or avoiding reliance on the affected versions for sensitive data hashing.