{"id":"DEBIAN-CVE-2026-84439","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.  A 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.  This issue affects Apache ZooKeeper: from 3.9.0 through 3.9.5, from 3.8.0 through 3.8.6.  Users are recommended to upgrade to version 3.9.6 or 3.8.7, which fixes the issue.","modified":"2026-09-26T16:00:09.584121180Z","published":"2026-09-16T10:16:53.433Z","upstream":["CVE-2026-84439"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-84439"}],"affected":[{"package":{"name":"zookeeper","ecosystem":"Debian:12","purl":"pkg:deb/debian/zookeeper?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.8.0-11","3.8.0-11+deb12u1","3.8.0-11+deb12u2","3.9.1-1","3.9.2-1","3.9.2-2","3.9.3-1","3.9.3-2","3.9.4-1","3.9.4-2","3.9.5-1","3.9.5-2","3.9.6-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-84439.json"}},{"package":{"name":"zookeeper","ecosystem":"Debian:13","purl":"pkg:deb/debian/zookeeper?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.9.3-1","3.9.3-1+deb13u1","3.9.3-2","3.9.4-1","3.9.4-2","3.9.5-1","3.9.5-2","3.9.6-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-84439.json"}},{"package":{"name":"zookeeper","ecosystem":"Debian:14","purl":"pkg:deb/debian/zookeeper?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.9.6-1"}]}],"versions":["3.9.3-1","3.9.3-2","3.9.4-1","3.9.4-2","3.9.5-1","3.9.5-2"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-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"}]}