CVE-2026-84439

NameCVE-2026-84439
DescriptionWhen 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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs1148409

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
zookeeper (PTS)bookworm3.8.0-11+deb12u2vulnerable
bookworm (security)3.8.0-11+deb12u1vulnerable
trixie3.9.3-1+deb13u1vulnerable
forky, sid3.9.6-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
zookeepersource(unstable)3.9.6-11148409

Notes

https://lists.apache.org/thread/b7qnjvqjh393l0j07tmnb5ggg40sx3m6

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