CVE-2026-94206 PUBLISHED

Cloak PBKDF2 field ignores the configured iteration count and runs only :size rounds

Assigner: EEF
Reserved: 24.09.2026 Published: 06.10.2026 Updated: 06.10.2026

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.

Metrics

CVSS 4.0

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS Score: 6.3

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	Low	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	Present	Availability	None	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

Product Status

Vendor	danielberkompas
Product	cloak_ecto
Versions	Default: unaffected affected from 1.0.0-alpha.0 to * (excl.)

Vendor	danielberkompas
Product	cloak_ecto
Versions	Default: unaffected affected from a8fa1642b02f1c445a1ee8794c9095eb0921f8f3 to * (excl.)

Vendor	danielberkompas
Product	cloak
Versions	Default: unaffected affected from 0.7.0 to 1.0.0-alpha.0 (excl.)

Vendor	danielberkompas
Product	cloak
Versions	Default: unaffected affected from 8699e6417a162c39d9f0ef63511bd23d3f38d1d2 to 681c9702b7cd9afe0e5a840751ab009f550c69a9 (excl.)

Workarounds

Override dump/1 in the field module that uses Cloak.Ecto.PBKDF2, so that it calls :pbkdf2.pbkdf2/5 with the configured :iterations and :size. Then recompute all stored hashes, because the existing values no longer match.

Credits

Peter Ullrich finder
Peter Ullrich reporter
Jonatan Männchen / EEF coordinator

References

Problem Types

CWE-916 Use of Password Hash With Insufficient Computational Effort CWE

Impacts

An attacker who obtains a database dump and the PBKDF2 secret can recover hashed values with low entropy, such as email addresses, by offline guessing at a cost far below what the configuration promises.