{"id":"CVE-2026-95105","aliases":["EEF-CVE-2026-95105","EUVD-2026-93090","GHSA-hxq7-6hm2-6wvg"],"status":"published","title":"Cloak AES-CTR cipher lacks ciphertext authentication, allowing chosen-plaintext forgery by bit flipping","description":"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.","severity":{"version":"4.0","score":8.2,"vector":"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","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00132,"percentile":0.02855,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-649"],"published":"2026-10-06T08:37:56Z","modified":"2026-10-28T02:30:25Z","affected":[{"source":"osv","ecosystem":"Hex","package":"cloak","ranges":[{"type":"SEMVER","events":[{"introduced":"0.1.0-pre"}]}],"versions":["0.1.0","0.1.0-pre","0.2.0","0.2.1","0.2.2","0.3.1","0.3.2","0.3.3","0.4.0","0.5.0","0.6.0","0.6.1","0.6.2","0.7.0","0.7.0-alpha.1","0.7.0-alpha.2","0.8.0","0.9.0","0.9.1","0.9.2","1.0.0","1.0.0-alpha.0","1.0.1","1.0.2","1.0.3","1.1.0","1.1.1","1.1.2","1.1.3","1.1.4"]}],"products":[{"vendor":"danielberkompas","product":"cloak"}],"references":[{"url":"https://cna.erlef.org/cves/CVE-2026-95105.html","tags":["related","third-party-advisory","exploit","advisory","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-95105","tags":["related","web"]},{"url":"https://github.com/danielberkompas/cloak/commit/2bd17019e285b55c5c218cc842537bf9280f24c3","tags":["related","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-95105","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-hxq7-6hm2-6wvg"},{"url":"https://github.com","tags":["web"]},{"url":"https://repo.hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/95xxx/CVE-2026-95105.json","tags":["advisory"]},{"url":"https://github.com/danielberkompas/cloak","tags":["package"]},{"url":"https://hex.pm/packages/cloak","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-95105","title":"Cloak AES-CTR cipher lacks ciphertext authentication, allowing chosen-plaintext forgery by bit flipping","description":"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.","status":"published","published":"2026-10-06T08:37:56.987Z","modified":"2026-10-06T11:40:42.775Z","cvss":[{"version":"4.0","score":8.2,"vector":"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","level":"high","assessor":"cna"}],"cwes":["CWE-649"],"updated_at":"2026-11-02T14:20:05.505362Z"}],"euvd":[{"id":"EUVD-2026-93090","description":"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.","status":"published","published":"2026-10-06T08:37:56Z","modified":"2026-10-06T11:40:42Z","cvss":[{"version":"4.0","score":8.2,"vector":"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","level":"high"}],"updated_at":"2026-11-02T17:27:37.923108Z"}],"ghsa":[{"id":"GHSA-hxq7-6hm2-6wvg","title":"Reliance on Obfuscation or Encryption of Security-Relevant Inputs without Integrity Checking...","description":"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.","status":"published","published":"2026-10-06T09:31:28Z","modified":"2026-10-06T09:31:29Z","cvss":[{"version":"4.0","score":8.2,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"}],"cwes":["CWE-649"],"updated_at":"2026-11-02T15:12:49.87154Z"}],"nvd":[{"id":"CVE-2026-95105","description":"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.","status":"published","published":"2026-10-06T09:17:57.2Z","modified":"2026-10-06T15:03:59.427Z","cvss":[{"version":"4.0","score":8.2,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"}],"cwes":["CWE-649"],"updated_at":"2026-11-02T14:12:54.129949Z"}],"osv":[{"id":"CVE-2026-95105","title":"Cloak AES-CTR cipher lacks ciphertext authentication, allowing chosen-plaintext forgery by bit flipping","description":"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.","status":"published","published":"2026-10-06T08:37:56.987Z","modified":"2026-10-28T02:30:25.102103844Z","cvss":[{"version":"4.0","score":8.2,"vector":"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","level":"high"}],"cwes":["CWE-649"],"updated_at":"2026-11-02T15:45:20.931171Z"},{"id":"EEF-CVE-2026-95105","title":"Cloak AES-CTR cipher lacks ciphertext authentication, allowing chosen-plaintext forgery by bit flipping","description":"## Summary\n\nReliance 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.\n\n## Proof of concept\n\n1. Encrypt `\"role=user \"` with `Cloak.Ciphers.AES.CTR.encrypt/2` and a random 32-byte key.\n2. Without the key, XOR the last 10 bytes of the result (the ciphertext body) with `:crypto.exor(\"role=user \", \"role=admin\")`. Leave the key tag and the IV unchanged.\n3. Call `Cloak.Ciphers.AES.CTR.decrypt/2` on the modified value. It returns `{:ok, \"role=admin\"}`.\n\n## Impact\n\nAn 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.\n\n## Workarounds\n\nConfigure 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.","status":"published","published":"2026-10-06T08:37:56.987Z","modified":"2026-10-06T08:45:03.181687744Z","cvss":[{"version":"4.0","score":8.2,"vector":"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","level":"high"}],"cwes":["CWE-649"],"updated_at":"2026-11-02T15:46:33.520522Z"}]}}