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DEBIAN-CVE-2026-84501

Type: advisorySource: OSV1 source record

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.

Announced Source revision 1
Original source ↗

DEBIAN-CVE-2026-84501

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:DEBIAN-CVE-2026-84501

zookeeper

Source reference: /affected/0/package/name

Affected versions
3.8.0-11

Source reference: /affected/0/versions

3.8.0-11+deb12u1

Source reference: /affected/0/versions

3.8.0-11+deb12u2

Source reference: /affected/0/versions

3.9.1-1

Source reference: /affected/0/versions

3.9.2-1

Source reference: /affected/0/versions

3.9.2-2

Source reference: /affected/0/versions

3.9.3-1

Source reference: /affected/0/versions

3.9.3-2

Source reference: /affected/0/versions

3.9.4-1

Source reference: /affected/0/versions

3.9.4-2

Source reference: /affected/0/versions

3.9.5-1

Source reference: /affected/0/versions

3.9.5-2

Source reference: /affected/0/versions

3.9.6-1

Source reference: /affected/0/versions

Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

zookeeper

Source reference: /affected/1/package/name

Affected versions
3.9.3-1

Source reference: /affected/1/versions

3.9.3-1+deb13u1

Source reference: /affected/1/versions

3.9.3-2

Source reference: /affected/1/versions

3.9.4-1

Source reference: /affected/1/versions

3.9.4-2

Source reference: /affected/1/versions

3.9.5-1

Source reference: /affected/1/versions

3.9.5-2

Source reference: /affected/1/versions

3.9.6-1

Source reference: /affected/1/versions

Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

zookeeper

Source reference: /affected/2/package/name

Affected versions
3.9.3-1

Source reference: /affected/2/versions

3.9.3-2

Source reference: /affected/2/versions

3.9.4-1

Source reference: /affected/2/versions

3.9.4-2

Source reference: /affected/2/versions

3.9.5-1

Source reference: /affected/2/versions

3.9.5-2

Source reference: /affected/2/versions

Fixed versions
3.9.6-1

Source reference: /affected/2/ranges

Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          }
        ]
      }
    ],
    "package": {
      "name": "zookeeper",
      "purl": "pkg:deb/debian/zookeeper?arch=source&distro=bookworm",
      "ecosystem": "Debian:12"
    },
    "versions": [
      "3.8.0-11",
      "3.8.0-11+deb12u1",
      "3.8.0-11+deb12u2",
      "3.9.1-1",
      "3.9.2-1",
      "3.9.2-2",
      "3.9.3-1",
      "3.9.3-2",
      "3.9.4-1",
      "3.9.4-2",
      "3.9.5-1",
      "3.9.5-2",
      "3.9.6-1"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-84501.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          }
        ]
      }
    ],
    "package": {
      "name": "zookeeper",
      "purl": "pkg:deb/debian/zookeeper?arch=source&distro=trixie",
      "ecosystem": "Debian:13"
    },
    "versions": [
      "3.9.3-1",
      "3.9.3-1+deb13u1",
      "3.9.3-2",
      "3.9.4-1",
      "3.9.4-2",
      "3.9.5-1",
      "3.9.5-2",
      "3.9.6-1"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-84501.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "3.9.6-1"
          }
        ]
      }
    ],
    "package": {
      "name": "zookeeper",
      "purl": "pkg:deb/debian/zookeeper?arch=source&distro=forky",
      "ecosystem": "Debian:14"
    },
    "versions": [
      "3.9.3-1",
      "3.9.3-2",
      "3.9.4-1",
      "3.9.4-2",
      "3.9.5-1",
      "3.9.5-2"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-84501.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  }
]

Publisher severity

No explicit severity was provided.

Event
#58490 · Revision 1
Added to Heist Feed
Publisher date
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