{"id":"CVE-2026-84439","state":"PUBLISHED","title":"Apache ZooKeeper: Audit log injection via unsanitized output from multiple sources","description":"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.","publishedAt":"2026-09-16T09:27:46.439Z","updatedAt":"2026-09-17T19:14:53.953Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","source":"CISA-ADP"},"assigner":"apache","products":["Apache Software Foundation Apache ZooKeeper"],"affected":[{"vendor":"Apache Software Foundation","product":"Apache ZooKeeper","packageName":"org.apache.zookeeper:zookeeper","packageURL":"pkg:maven/org.apache.zookeeper/zookeeper","defaultStatus":"unaffected","versions":[{"version":"3.9.0","status":"affected","lessThanOrEqual":"3.9.5","versionType":"maven"},{"version":"3.8.0","status":"affected","lessThanOrEqual":"3.8.6","versionType":"maven"}],"collectionURL":"https://repo.maven.apache.org/maven2"}],"references":["https://lists.apache.org/thread/b7qnjvqjh393l0j07tmnb5ggg40sx3m6","http://www.openwall.com/lists/oss-security/2026/09/15/6"],"weaknesses":["CWE-117"],"ingestedAt":"2026-10-29T20:13:15.269Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/84xxx/CVE-2026-84439.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-84439","state":"PUBLISHED","datePublished":"2026-09-16T09:27:46.439Z","dateUpdated":"2026-09-17T19:14:53.953Z","assignerShortName":"apache","assignerOrgId":"f0158376-9dc2-43b6-827c-5f631a4d8d09","dateReserved":"2026-09-01T19:22:00.838Z"},"containers":{"cna":{"title":"Apache ZooKeeper: Audit log injection via unsanitized output from multiple sources","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Apache Software Foundation","product":"Apache ZooKeeper","packageName":"org.apache.zookeeper:zookeeper","packageURL":"pkg:maven/org.apache.zookeeper/zookeeper","defaultStatus":"unaffected","versions":[{"version":"3.9.0","status":"affected","lessThanOrEqual":"3.9.5","versionType":"maven"},{"version":"3.8.0","status":"affected","lessThanOrEqual":"3.8.6","versionType":"maven"}],"collectionURL":"https://repo.maven.apache.org/maven2"}],"references":[{"url":"https://lists.apache.org/thread/b7qnjvqjh393l0j07tmnb5ggg40sx3m6","tags":["vendor-advisory"]}],"metrics":[{"other":{"type":"Textual description of severity","content":{"text":"important"}},"scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-117","description":"CWE-117 Improper output neutralization for logs","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"apache","orgId":"f0158376-9dc2-43b6-827c-5f631a4d8d09","dateUpdated":"2026-09-16T09:27:46.439Z"},"source":{"discovery":"UNKNOWN"},"credits":[{"lang":"en","value":"Youlong Chen Institute of Computing Technology <chenyoulong20g@ict.ac.cn>","type":"reporter"}],"x_generator":{"engine":"Vulnogram 1.0.3"}},"adp":[{"title":"CVE Program Container","references":[{"url":"http://www.openwall.com/lists/oss-security/2026/09/15/6"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2026-09-16T10:12:00.087Z"}},{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":5.3,"attackVector":"NETWORK","baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","integrityImpact":"LOW","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"NONE","privilegesRequired":"NONE","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-09-17T19:14:36.442526Z","id":"CVE-2026-84439","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-17T19:14:53.953Z"}}]}}}