Reliance on Obfuscation or Encryption of Security-Relevant Inputs without Integrity Checking vulnerability in danielberkompas cloak allows an attacker with write access to stored ciphertext to make it decrypt to a chosen value via bit flipping.
\nCloak.Ciphers.AES.CTR encrypts with AES-256 in CTR mode and stores the key tag, the IV and the ciphertext with no MAC. decrypt/2 checks only the key tag and the minimum length before it returns the plaintext, and Cloak.Ciphers.Deprecated.AES.CTR decrypts the legacy format the same way. CTR is a stream cipher, so a value XORed into the stored ciphertext is XORed into the plaintext at the same offset. An attacker who can write to the encrypted store (for example through SQL injection or a compromised replica) and who knows or can guess a stored plaintext can replace it with any value of the same length. The application receives that value with no error.
This issue affects cloak: from 0.1.0-pre onward.
"},{"base64":false,"type":"text/markdown","value":"Reliance on Obfuscation or Encryption of Security-Relevant Inputs without Integrity Checking vulnerability in danielberkompas cloak allows an attacker with write access to stored ciphertext to make it decrypt to a chosen value via bit flipping.\n\n`Cloak.Ciphers.AES.CTR` encrypts with AES-256 in CTR mode and stores the key tag, the IV and the ciphertext with no MAC. `decrypt/2` checks only the key tag and the minimum length before it returns the plaintext, and `Cloak.Ciphers.Deprecated.AES.CTR` decrypts the legacy format the same way. CTR is a stream cipher, so a value XORed into the stored ciphertext is XORed into the plaintext at the same offset. An attacker who can write to the encrypted store (for example through SQL injection or a compromised replica) and who knows or can guess a stored plaintext can replace it with any value of the same length. The application receives that value with no error.\n\nThis issue affects cloak: from 0.1.0-pre onward."}],"value":"Reliance on Obfuscation or Encryption of Security-Relevant Inputs without Integrity Checking vulnerability in danielberkompas cloak allows an attacker with write access to stored ciphertext to make it decrypt to a chosen value via bit flipping.\n\nCloak.Ciphers.AES.CTR encrypts with AES-256 in CTR mode and stores the key tag, the IV and the ciphertext with no MAC. decrypt/2 checks only the key tag and the minimum length before it returns the plaintext, and Cloak.Ciphers.Deprecated.AES.CTR decrypts the legacy format the same way. CTR is a stream cipher, so a value XORed into the stored ciphertext is XORed into the plaintext at the same offset. An attacker who can write to the encrypted store (for example through SQL injection or a compromised replica) and who knows or can guess a stored plaintext can replace it with any value of the same length. The application receives that value with no error.\n\nThis issue affects cloak: from 0.1.0-pre onward."}],"impacts":[{"capecId":"CAPEC-39","descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"An attacker who can write to the encrypted store can set encrypted fields with known or guessable contents, such as roles, flags, or fixed-format records, to values of their choice without the key. The application decrypts and trusts the forged value.
"},{"base64":false,"type":"text/markdown","value":"An attacker who can write to the encrypted store can set encrypted fields with known or guessable contents, such as roles, flags, or fixed-format records, to values of their choice without the key. The application decrypts and trusts the forged value."}],"value":"An attacker who can write to the encrypted store can set encrypted fields with known or guessable contents, such as roles, flags, or fixed-format records, to values of their choice without the key. The application decrypts and trusts the forged value."}]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":8.2,"baseSeverity":"HIGH","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:N/VI:H/VA:N/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-649","description":"CWE-649 Reliance on Obfuscation or Encryption of Security-Relevant Inputs without Integrity Checking","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-10-06T08:37:56.987Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"references":[{"name":"EEF CNA record for CVE-2026-95105","tags":["related","third-party-advisory"],"url":"https://cna.erlef.org/cves/CVE-2026-95105.html"},{"name":"OSV record EEF-CVE-2026-95105","tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-95105"},{"name":"Introducing commit 2bd1701 in danielberkompas/cloak","tags":["related"],"url":"https://github.com/danielberkompas/cloak/commit/2bd17019e285b55c5c218cc842537bf9280f24c3"}],"source":{"discovery":"EXTERNAL"},"title":"Cloak AES-CTR cipher lacks ciphertext authentication, allowing chosen-plaintext forgery by bit flipping","workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Configure the vault with Cloak.Ciphers.AES.GCM as the default cipher and re-encrypt existing values, for example with the cloak.migrate.ecto task from cloak_ecto. Then remove Cloak.Ciphers.AES.CTR and Cloak.Ciphers.Deprecated.AES.CTR from the vault configuration, so that ciphertext in the CTR format is no longer decrypted. AES-GCM authenticates the ciphertext and rejects modified values.
\"role=user \" with Cloak.Ciphers.AES.CTR.encrypt/2 and a random 32-byte key.:crypto.exor(\"role=user \", \"role=admin\"). Leave the key tag and the IV unchanged.Cloak.Ciphers.AES.CTR.decrypt/2 on the modified value. It returns {:ok, \"role=admin\"}.