DEBIAN-CVE-2026-84501
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.
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/versions3.8.0-11+deb12u1Source reference:
/affected/0/versions3.8.0-11+deb12u2Source reference:
/affected/0/versions3.9.1-1Source reference:
/affected/0/versions3.9.2-1Source reference:
/affected/0/versions3.9.2-2Source reference:
/affected/0/versions3.9.3-1Source reference:
/affected/0/versions3.9.3-2Source reference:
/affected/0/versions3.9.4-1Source reference:
/affected/0/versions3.9.4-2Source reference:
/affected/0/versions3.9.5-1Source reference:
/affected/0/versions3.9.5-2Source reference:
/affected/0/versions3.9.6-1Source 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/versions3.9.3-1+deb13u1Source reference:
/affected/1/versions3.9.3-2Source reference:
/affected/1/versions3.9.4-1Source reference:
/affected/1/versions3.9.4-2Source reference:
/affected/1/versions3.9.5-1Source reference:
/affected/1/versions3.9.5-2Source reference:
/affected/1/versions3.9.6-1Source 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/versions3.9.3-2Source reference:
/affected/2/versions3.9.4-1Source reference:
/affected/2/versions3.9.4-2Source reference:
/affected/2/versions3.9.5-1Source reference:
/affected/2/versions3.9.5-2Source 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