CVE-2026-94206 in cloak
Summary
by MITRE • 10/06/2026
Use of Password Hash With Insufficient Computational Effort vulnerability in danielberkompas cloak_ecto and danielberkompas cloak allows an attacker who holds the hashed values and the configured secret to brute-force low-entropy plaintexts much faster than configured.
The dump/1 callback that Cloak.Ecto.PBKDF2 (Cloak.Fields.PBKDF2 in cloak before the Ecto code moved to cloak_ecto) injects into a field module calls :pbkdf2.pbkdf2/4 with config[:size] in the iteration-count position. The :iterations setting is validated but never used. With the cloak_ecto defaults (iterations: 600_000, size: 32) each hash runs 32 PBKDF2 rounds instead of 600,000, so offline guessing of values such as email addresses costs about 18,750 times less than configured.
This issue affects cloak_ecto: from 1.0.0-alpha.0 onward; cloak: from 0.7.0 before 1.0.0-alpha.0.
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Analysis
by VulDB Data Team • 10/06/2026
The vulnerability identified in the Cloak and Cloak.Ecto libraries represents a critical misconfiguration of cryptographic parameters that severely undermines password hashing security. This flaw, classified under CWE-916 as Use of Password Hash With Insufficient Computational Effort, stems from an implementation error where the intended iteration count for key derivation is ignored during the actual hash generation process. The vulnerability specifically impacts danielberkompas/cloak_ecto versions 1.0.0-alpha.0 and later, as well as danielberkompas/cloak versions prior to 1.0.0-alpha.0. In these affected versions, developers configure a high number of iterations intended to slow down brute-force attacks, but the underlying code fails to utilize this setting effectively, resulting in significantly weaker protection than anticipated by system administrators and security engineers.
The technical root cause lies within the dump/1 callback function injected into field modules by Cloak.Ecto.PBKDF2 or its predecessor Cloak.Fields.PBKDF2. This callback is responsible for transforming plaintext values into hashed representations before storage in a database. The code invokes the :pbkdf2.pbkdf2/4 function, which accepts parameters including salt, key length, iterations, and other options. However, due to a coding error, the configuration value designated as config[:size] is incorrectly passed into the iteration-count position of the PBKDF2 algorithm call. Consequently, the :iterations setting defined in the application configuration is validated for presence but never actually applied during the hashing operation. This means that regardless of how high an administrator sets the iterations parameter to increase computational cost, the system proceeds with a default or incorrect low value derived from the size parameter instead.
The operational impact of this vulnerability is substantial, particularly regarding offline password guessing attacks. In a typical secure configuration for Cloak.Ecto.PBKDF2, the defaults are set to an iteration count of 600,000 and a key size of 32 bytes. Due to the bug, each hash actually executes only 32 rounds of PBKDF2 instead of the intended 600,000. This discrepancy results in a computational cost reduction factor of approximately 18,750 times compared to the configured security level. For an attacker who obtains hashed values and knows or can guess the secret key used for encryption, this weakness allows them to perform brute-force attacks against low-entropy plaintexts with drastically reduced effort. Values such as email addresses, which often have limited entropy, become trivially recoverable within seconds rather than requiring significant computational resources over extended periods.
From a threat modeling perspective, this vulnerability aligns with the ATT&CK technique T1110.003, specifically Brute Force: Password Guessing for Remote Services or Local Access if database access is compromised. The ease of reversing these hashes means that any breach resulting in data exfiltration could lead to immediate credential compromise for users who reuse passwords across services. Since the hashing function fails to provide adequate resistance against offline attacks, the confidentiality and integrity assurances provided by the encryption layer are effectively nullified for weak secrets. This is particularly dangerous because many applications rely on these libraries to protect sensitive user identifiers or authentication tokens that may not be sufficiently random.
Mitigation requires immediate action from application maintainers using affected versions of Cloak or Cloak.Ecto. The primary remediation step is to upgrade the library dependencies to patched versions where this parameter mapping error has been corrected, ensuring that the :iterations configuration value is correctly passed to the PBKDF2 algorithm's iteration count argument. Until an update can be applied, developers should consider implementing a workaround by manually configuring the hashing module or switching to alternative cryptographic libraries that do not exhibit this specific implementation flaw. Additionally, it is advisable to enforce stronger password policies and increase entropy requirements for any secrets stored using these vulnerable functions to partially compensate for the reduced computational effort during hash generation. Regular security audits of dependency configurations are recommended to prevent similar misconfigurations in future deployments.