{
  "cveId": "CVE-2026-84501",
  "url": "https://patchblox.com/security/cve/CVE-2026-84501",
  "summary": "CVE-2026-84501 is fixed in zookeeper on 1 platform by DEBIAN-CVE-2026-84501 (version 3.9.6-1), released September 26, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "zookeeper: An unauthenticated attacker can inject arbitrary fake log lines into Apache ZooKeeper\u0027s operational log by sending a...",
  "description": "An unauthenticated attacker can inject arbitrary fake log lines into Apache ZooKeeper\u0027s operational log by sending a crafted add_auth(\u0022ensemble\u0022, ...) request containing newline characters (\\n). When the ensemble name doesn\u0027t match, EnsembleAuthenticationProvider.handleAuthentication() logs the raw, unsanitized name via LOG.warn(). Because SLF4J\u0027s {} placeholder preserves embedded newlines, the attacker can forge complete log entries \u2014 with arbitrary timestamps, log levels, class names, and messages \u2014 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.",
  "published": "2026-09-16T10:16:53Z",
  "severity": "medium",
  "cvss": 5.3,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
  "epss": 0.00742,
  "epssPercentile": 0.54944,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "zookeeper",
      "release": "Debian 14",
      "fixedVersion": "3.9.6-1",
      "fix": "DEBIAN-CVE-2026-84501",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-84501",
      "released": "2026-09-26T19:52:05Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T01:18:40Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}