CVE-2026-84439

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.

CVSS

No CVSS.

References

Link	Resource
https://lists.apache.org/thread/b7qnjvqjh393l0j07tmnb5ggg40sx3m6
http://www.openwall.com/lists/oss-security/2026/09/15/6

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-16 10:16

Updated : 2026-09-16 11:16

NVD link : CVE-2026-84439

Mitre link : CVE-2026-84439

CVE.ORG link : CVE-2026-84439

JSON object : View

Products Affected

No product.

CWE

CWE-117

Improper Output Neutralization for Logs

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