CVE-2026-84501

Description

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. 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 3.8.7 or 3.9.6, which fixes the issue.

Traduire en français

Produits concernés

• Apache Software Foundation Apache ZooKeeper
• Apache zookeeper

Scores CVSS

Faiblesses (CWE)

• CWE-117

Références

• https://lists.apache.org/thread/ohby1g6zjt72p0w79rhbr41nczzvr33y Mailing ListVendor Advisory
• http://www.openwall.com/lists/oss-security/2026/09/15/7 Mailing List

Ailleurs

• NVD
• CVE.org
• CIRCL Vulnerability-Lookup
• CERT-FR
• GitHub Advisories