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.
\nThe 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.
"},{"base64":false,"type":"text/markdown","value":"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.\n\nThe `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.\n\nThis issue affects cloak_ecto: from 1.0.0-alpha.0 onward; cloak: from 0.7.0 before 1.0.0-alpha.0."}],"value":"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.\n\nThe 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.\n\nThis issue affects cloak_ecto: from 1.0.0-alpha.0 onward; cloak: from 0.7.0 before 1.0.0-alpha.0."}],"impacts":[{"capecId":"CAPEC-55","descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"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.
"},{"base64":false,"type":"text/markdown","value":"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."}],"value":"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."}]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":6.3,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"NONE","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-916","description":"CWE-916 Use of Password Hash With Insufficient Computational Effort","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-10-06T08:38:04.584Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"references":[{"name":"EEF CNA record for CVE-2026-94206","tags":["related","third-party-advisory"],"url":"https://cna.erlef.org/cves/CVE-2026-94206.html"},{"name":"OSV record EEF-CVE-2026-94206","tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-94206"},{"name":"Introducing commit a8fa164 in danielberkompas/cloak_ecto","tags":["related"],"url":"https://github.com/danielberkompas/cloak_ecto/commit/a8fa1642b02f1c445a1ee8794c9095eb0921f8f3"},{"name":"Introducing commit 8699e64 in danielberkompas/cloak","tags":["related"],"url":"https://github.com/danielberkompas/cloak/commit/8699e6417a162c39d9f0ef63511bd23d3f38d1d2"},{"name":"Fix commit 681c970 in danielberkompas/cloak","tags":["patch"],"url":"https://github.com/danielberkompas/cloak/commit/681c9702b7cd9afe0e5a840751ab009f550c69a9"}],"source":{"discovery":"EXTERNAL"},"title":"Cloak PBKDF2 field ignores the configured iteration count and runs only :size rounds","workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"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.
use Cloak.Ecto.PBKDF2 and configure only a :secret, so that the defaults iterations: 600_000 and size: 32 apply.dump/1 on a value.:pbkdf2.pbkdf2({:hmac, :sha256}, value, secret, 32) and with the same call at 600,000 rounds. It matches the 32-round hash, not the 600,000-round hash, and returns in microseconds instead of about one second.