{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-84501","assignerOrgId":"f0158376-9dc2-43b6-827c-5f631a4d8d09","state":"PUBLISHED","assignerShortName":"apache","dateReserved":"2026-09-01T20:56:03.868Z","datePublished":"2026-09-16T09:28:10.294Z","dateUpdated":"2026-09-16T19:43:09.161Z"},"containers":{"cna":{"providerMetadata":{"orgId":"f0158376-9dc2-43b6-827c-5f631a4d8d09","shortName":"apache","dateUpdated":"2026-09-16T09:28:10.294Z"},"title":"Apache ZooKeeper: Operational log forgery via newline injection in EnsembleAuthenticationProvider","problemTypes":[{"descriptions":[{"description":"CWE-117 Improper output neutralization for logs","lang":"en","cweId":"CWE-117","type":"CWE"}]}],"source":{"discovery":"UNKNOWN"},"affected":[{"vendor":"Apache Software Foundation","product":"Apache ZooKeeper","collectionURL":"https://repo.maven.apache.org/maven2","packageName":"org.apache.zookeeper:zookeeper","packageURL":"pkg:maven/org.apache.zookeeper/zookeeper","versions":[{"status":"affected","version":"3.9.0","lessThanOrEqual":"3.9.5","versionType":"maven"},{"status":"affected","version":"3.8.0","lessThanOrEqual":"3.8.6","versionType":"maven"}],"defaultStatus":"unaffected"}],"descriptions":[{"value":"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.","lang":"en","supportingMedia":[{"type":"text/html","base64":false,"value":"<p>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.<br><span><br>This issue affects Apache ZooKeeper: from 3.9.0 through 3.9.5, from 3.8.0 through 3.8.6.<br></span><span><br>Users are recommended to upgrade to version 3.8.7 or 3.9.6, which fixes the issue.</span></p>"}]}],"references":[{"url":"https://lists.apache.org/thread/ohby1g6zjt72p0w79rhbr41nczzvr33y","tags":["vendor-advisory"]}],"metrics":[{"other":{"type":"Textual description of severity","content":{"text":"moderate"}},"scenarios":[{"lang":"en","value":"GENERAL"}]}],"credits":[{"lang":"en","value":"Youlong Chen Institute of Computing Technology <chenyoulong20g@ict.ac.cn>","type":"finder"}],"x_generator":{"engine":"Vulnogram 1.0.3"}},"adp":[{"title":"CVE Program Container","references":[{"url":"http://www.openwall.com/lists/oss-security/2026/09/15/7"}],"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2026-09-16T10:12:02.894Z"}},{"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":"2026-09-16T19:42:27.138755Z","id":"CVE-2026-84501","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-09-16T19:43:09.161Z"}}]}}