{"id":"CVE-2026-84971","title":"Improper handling of an unexpected value size in the decryption path of a client-side encryption library can cause a failed internal check that terminates the process using the library","summary":"Improper handling of an unexpected value size in the decryption path of a client-side encryption library can cause a failed internal check that terminates the process using the library. A party able to place a suitably formed encrypted v…","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-617"],"vendor":"mongodb","product":"libmongocrypt","affected":["libmongocrypt >= 1.7.0, < 1.20.4"],"patched":["libmongocrypt 1.20.4"],"published":"2026-09-03","updated":"2026-09-17","sourceUpdated":"2026-09-17T13:59:13.180","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-84971","references":[{"url":"https://jira.mongodb.org/browse/MONGOCRYPT-971","label":"cna@mongodb.com"}],"tags":["nvd"],"epss":0.00157,"epssPercentile":0.05298,"ingestedAt":"2026-09-17T14:19:30.938Z","slug":"CVE-2026-84971","body":"## Overview\n\nImproper handling of an unexpected value size in the decryption path of a client-side encryption library can cause a failed internal check that terminates the process using the library. A party able to place a suitably formed encrypted value where an application will decrypt it, or able to control the responses the application receives, may cause that application to stop running.\n\n## Affected\n\n- `libmongocrypt >= 1.7.0, < 1.20.4`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `libmongocrypt 1.20.4`","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}