CVE-2026-84439

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-84439", "assignerOrgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09", "state": "PUBLISHED", "assignerShortName": "apache", "dateReserved": "2026-09-01T19:22:00.838Z", "datePublished": "2026-09-16T09:27:46.439Z", "dateUpdated": "2026-09-17T19:14:53.953Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09", "shortName": "apache", "dateUpdated": "2026-09-16T09:27:46.439Z"}, "title": "Apache ZooKeeper: Audit log injection via unsanitized output from multiple sources", "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": "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\u00a0key=value\u00a0format, the injected tabs are parsed as legitimate field separators, allowing the attacker to spoof audit results (e.g., injecting\u00a0result=success), forge operation types, and corrupt forensic evidence.\n\nA log injection vulnerability in Apache ZooKeeper allows a client that can call\u00a0setACL\u00a0to inject forged key-value fields into\u00a0zookeeper_audit.log. When audit logging is enabled, the server serializes attacker-controlled digest ACL ids into the\u00a0acl=\u00a0audit field without escaping tab characters. Because audit events are emitted as tab-separated\u00a0key=value\u00a0records, a crafted ACL id can make one successful\u00a0setAcl\u00a0event appear to contain forged fields such as\u00a0operation=delete\u00a0and\u00a0znode=/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.", "lang": "en", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>When audit logging is enabled (<code>zookeeper.audit.enable=true</code>), an unauthenticated attacker can inject arbitrary fields into Apache ZooKeeper's audit log by sending a digest authentication request with tab characters (<code>\\t</code>) embedded in the username. Because the audit log uses tab-separated&nbsp;<code>key=value</code>&nbsp;format, the injected tabs are parsed as legitimate field separators, allowing the attacker to spoof audit results (e.g., injecting&nbsp;<code>result=success</code>), forge operation types, and corrupt forensic evidence.<br><span><br>A log injection vulnerability in Apache ZooKeeper allows a client that can call&nbsp;</span><code>setACL</code><span>&nbsp;</span><span>to inject forged key-value fields into</span><span>&nbsp;</span><code>zookeeper_audit.log</code><span>. When audit logging is enabled, the server serializes attacker-controlled digest ACL ids into the</span><span>&nbsp;</span><code>acl=</code><span>&nbsp;</span><span>audit field without escaping tab characters. Because audit events are emitted as tab-separated</span><span>&nbsp;</span><code>key=value</code><span>&nbsp;</span><span>records, a crafted ACL id can make one successful</span><span>&nbsp;</span><code>setAcl</code><span>&nbsp;</span><span>event appear to contain forged fields such as</span><span>&nbsp;</span><code>operation=delete</code><span>&nbsp;</span><span>and</span><span>&nbsp;</span><code>znode=/forged</code><span>. This undermines the integrity of downstream audit parsing, alerting, and incident response.</span><span><br></span><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 3.9.6 or 3.8.7, which fixes the issue.</span></p>"}]}], "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"}]}], "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": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2026-09-16T10:12:00.087Z"}}, {"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"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-17T19:14:53.953Z"}}]}}

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Because the audit log uses tab-separated\u00a0key=value\u00a0format, the injected tabs are parsed as legitimate field separators, allowing the attacker to spoof audit results (e.g., injecting\u00a0result=success), forge operation types, and corrupt forensic evidence.\n\nA log injection vulnerability in Apache ZooKeeper allows a client that can call\u00a0setACL\u00a0to inject forged key-value fields into\u00a0zookeeper_audit.log. When audit logging is enabled, the server serializes attacker-controlled digest ACL ids into the\u00a0acl=\u00a0audit field without escaping tab characters. Because audit events are emitted as tab-separated\u00a0key=value\u00a0records, a crafted ACL id can make one successful\u00a0setAcl\u00a0event appear to contain forged fields such as\u00a0operation=delete\u00a0and\u00a0znode=/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.", "supportingMedia": [{"type": "text/html", "value": "<p>When audit logging is enabled (<code>zookeeper.audit.enable=true</code>), an unauthenticated attacker can inject arbitrary fields into Apache ZooKeeper's audit log by sending a digest authentication request with tab characters (<code>\\t</code>) embedded in the username. Because the audit log uses tab-separated&nbsp;<code>key=value</code>&nbsp;format, the injected tabs are parsed as legitimate field separators, allowing the attacker to spoof audit results (e.g., injecting&nbsp;<code>result=success</code>), forge operation types, and corrupt forensic evidence.<br><span><br>A log injection vulnerability in Apache ZooKeeper allows a client that can call&nbsp;</span><code>setACL</code><span>&nbsp;</span><span>to inject forged key-value fields into</span><span>&nbsp;</span><code>zookeeper_audit.log</code><span>. When audit logging is enabled, the server serializes attacker-controlled digest ACL ids into the</span><span>&nbsp;</span><code>acl=</code><span>&nbsp;</span><span>audit field without escaping tab characters. Because audit events are emitted as tab-separated</span><span>&nbsp;</span><code>key=value</code><span>&nbsp;</span><span>records, a crafted ACL id can make one successful</span><span>&nbsp;</span><code>setAcl</code><span>&nbsp;</span><span>event appear to contain forged fields such as</span><span>&nbsp;</span><code>operation=delete</code><span>&nbsp;</span><span>and</span><span>&nbsp;</span><code>znode=/forged</code><span>. This undermines the integrity of downstream audit parsing, alerting, and incident response.</span><span><br></span><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 3.9.6 or 3.8.7, which fixes the issue.</span></p>", "base64": false}]}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-117", "description": "CWE-117 Improper output neutralization for logs"}]}], "providerMetadata": {"orgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09", "shortName": "apache", "dateUpdated": "2026-09-16T09:27:46.439Z"}}}, "cveMetadata": {"cveId": "CVE-2026-84439", "state": "PUBLISHED", "dateUpdated": "2026-09-16T10:12:00.087Z", "dateReserved": "2026-09-01T19:22:00.838Z", "assignerOrgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09", "datePublished": "2026-09-16T09:27:46.439Z", "assignerShortName": "apache"}, "dataVersion": "5.2"}

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{}

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