CVEvulnerability

CVE-2026-84501

5.3 MEDIUM Published 2026-09-16 Modified 2026-09-18 Official page ↗
Status
Analyzed
Published
2026-09-16
Last modified
2026-09-18
Assigner
[email protected]
CVSS 3.1 (134c704f-9b21-4f2e-91b3-4a467353bcc0)
5.3 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Weaknesses
CWE-117

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.

Affected configurations

• apache zookeeper (>= 3.8.0 < 3.8.7) • apache zookeeper (>= 3.9.0 < 3.9.6)

Related

Weakness · CWE (1)

  • CWE-117 Improper Output Neutralization for Logs weakness

References