Improper Output Neutralization for Logs Affecting zookeeper-3.9 package, versions <3.9.6-r0
Threat Intelligence
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Test your applications- Snyk IDSNYK-MINIMOSLATEST-ZOOKEEPER39-19957982
- published20 Sept 2026
- disclosed16 Sept 2026
Introduced: 16 Sep 2026
NewCVE-2026-84439 (opens in a new tab)How to fix?
Upgrade Minimos:latest zookeeper-3.9 to version 3.9.6-r0 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream zookeeper-3.9 package and not the zookeeper-3.9 package as distributed by Minimos.
See How to fix? for Minimos:latest relevant fixed versions and status.
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.
References
- https://www.cve.org/CVERecord?id=CVE-2026-84439
- https://github.com/advisories/GHSA-mxvw-9w3g-hmrq
- https://osv.dev/vulnerability/MINI-jvcg-72p3-4262
- https://osv.dev/vulnerability/CVE-2026-84439
- https://lists.apache.org/thread/b7qnjvqjh393l0j07tmnb5ggg40sx3m6
- http://www.openwall.com/lists/oss-security/2026/09/15/6