{"id":"CVE-2026-84439","summary":"Apache ZooKeeper: Audit log injection via unsanitized output from multiple sources","details":"When audit logging is enabled (zookeeper.audit.enable=true), an unauthenticated attacker can inject arbitrary fields into Apache ZooKeeper's audit log by sending a digest authentication request with tab characters (\\t) embedded in the username. Because the audit log uses tab-separated key=value format, the injected tabs are parsed as legitimate field separators, allowing the attacker to spoof audit results (e.g., injecting result=success), forge operation types, and corrupt forensic evidence.\n\nA log injection vulnerability in Apache ZooKeeper allows a client that can call setACL to inject forged key-value fields into zookeeper_audit.log. When audit logging is enabled, the server serializes attacker-controlled digest ACL ids into the acl= audit field without escaping tab characters. Because audit events are emitted as tab-separated key=value records, a crafted ACL id can make one successful setAcl event appear to contain forged fields such as operation=delete and znode=/forged. This undermines the integrity of downstream audit parsing, alerting, and incident response.\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 3.9.6 or 3.8.7, which fixes the issue.","aliases":["BIT-zookeeper-2026-84439"],"modified":"2026-09-20T11:46:42.558871089Z","published":"2026-09-16T09:27:46.439Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84439.json","unresolved_ranges":[{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"3.9.0"},{"last_affected":"3.9.5"},{"introduced":"3.8.0"},{"last_affected":"3.8.6"}]},{"extracted_events":[{"introduced":"3.9.0"},{"fixed":"3.9.5"},{"introduced":"3.8.0"},{"fixed":"3.8.6"}],"source":"DESCRIPTION"}],"cna_assigner":"apache","cwe_ids":["CWE-117"]},"references":[{"type":"WEB","url":"http://www.openwall.com/lists/oss-security/2026/09/15/6"},{"type":"WEB","url":"https://repo.maven.apache.org/maven2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84439.json"},{"type":"ADVISORY","url":"https://lists.apache.org/thread/b7qnjvqjh393l0j07tmnb5ggg40sx3m6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-84439"}],"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-2026-84439.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"}]}