{"id":"CVE-2026-84501","summary":"Apache ZooKeeper: Operational log forgery via newline injection in EnsembleAuthenticationProvider","details":"An unauthenticated attacker can inject arbitrary fake log lines into Apache ZooKeeper's operational log by sending a crafted add_auth(\"ensemble\", ...) request containing newline characters (\\n). When the ensemble name doesn't match, EnsembleAuthenticationProvider.handleAuthentication() logs the raw, unsanitized name via LOG.warn(). Because SLF4J's {} placeholder preserves embedded newlines, the attacker can forge complete log entries — with arbitrary timestamps, log levels, class names, and messages — that are visually indistinguishable from genuine ZooKeeper log output.\n\nThis issue affects Apache ZooKeeper: from 3.9.0 through 3.9.5, from 3.8.0 through 3.8.6.\n\nUsers are recommended to upgrade to version 3.8.7 or 3.9.6, which fixes the issue.","aliases":["BIT-zookeeper-2026-84501"],"modified":"2026-09-20T11:47:27.177447241Z","published":"2026-09-16T09:28:10.294Z","database_specific":{"cwe_ids":["CWE-117"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84501.json","unresolved_ranges":[{"extracted_events":[{"introduced":"3.9.0"},{"last_affected":"3.9.5"},{"introduced":"3.8.0"},{"last_affected":"3.8.6"}],"source":"AFFECTED_FIELD"},{"source":"DESCRIPTION","extracted_events":[{"introduced":"3.9.0"},{"fixed":"3.9.5"},{"introduced":"3.8.0"},{"fixed":"3.8.6"}]}],"cna_assigner":"apache"},"references":[{"type":"WEB","url":"http://www.openwall.com/lists/oss-security/2026/09/15/7"},{"type":"WEB","url":"https://repo.maven.apache.org/maven2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84501.json"},{"type":"ADVISORY","url":"https://lists.apache.org/thread/ohby1g6zjt72p0w79rhbr41nczzvr33y"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-84501"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/apache/zookeeper","events":[{"introduced":"97c181a40d6dd6ccb2fdad7fcdbd1fd74ab0b6c8"},{"fixed":"9085db92dd679e1e90a63bfe6ae6345ab6cbc4ae"},{"introduced":"1674a5e97f43bc38e9bf56b04f83a7ae34d68249"},{"fixed":"a355171b081b5b60749db8f19cca1528b0df936f"}],"database_specific":{"extracted_events":[{"introduced":"3.8.0"},{"fixed":"3.8.7"},{"introduced":"3.9.0"},{"fixed":"3.9.6"}],"source":"CPE_RANGE","cpe":"cpe:2.3:a:apache:zookeeper:*:*:*:*:*:*:*:*"}}],"versions":["release-3.9.5-0","release-3.9.5","release-3.9.4-2","release-3.9.4","release-3.9.4-1","release-3.9.4-0","release-3.9.3-2","release-3.9.3","release-3.9.3-1","release-3.9.3-0","release-3.9.2-0","release-3.9.2","release-3.9.1-0","release-3.9.1","release-3.9.0-1","release-3.9.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-84501.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"}]}