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": { "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-10-06T08:37:56.987Z" }, "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\"}.