---
id: CVE-2026-24281
title: >-
  Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse
  DNS (PTR) when IP SAN validation fails, allowing attackers who control or
  spoof PTR records to impersonate ZooKeeper servers or clients with a valid
  certifica…
summary: >-
  Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse
  DNS (PTR) when IP SAN validation fails, allowing attackers who control or
  spoof PTR records to impersonate ZooKeeper servers or clients with a valid
  certifica…
severity: high
cvss: 7.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-295
  - CWE-350
vendor: apache
product: zookeeper
affected:
  - 'zookeeper >= 3.8.0, < 3.8.6'
  - 'zookeeper >= 3.9.0, < 3.9.5'
patched:
  - zookeeper 3.9.5
published: '2026-03-07'
updated: '2026-07-03'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-24281'
references:
  - url: 'https://lists.apache.org/thread/088ddsbrzhd5lxzbqf5n24yg0mwh9jt2'
    label: security@apache.org
  - url: 'http://www.openwall.com/lists/oss-security/2026/03/07/4'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://access.redhat.com/errata/RHSA-2026:10184'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:14272'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:14276'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:34608'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:8509'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/security/cve/CVE-2026-24281'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2445449'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-24281.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-24281'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-24281'
  - url: 'https://access.redhat.com/errata/RHSA-2026:70421'
tags:
  - nvd
  - csaf
  - vex
  - red-hat
epss: 0.00633
epssPercentile: 0.48082
ingestedAt: '2026-07-03T14:03:36.866Z'
---

## Overview

Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It's important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.

## Affected

- `zookeeper >= 3.8.0, < 3.8.6`
- `zookeeper >= 3.9.0, < 3.9.5`

## Remediation

Upgrade past the affected range:

- `zookeeper 3.9.5`

## Vendor advisories

- **RHSA-2026:14276** · Red Hat · fixed in: Red Hat AMQ Broker 7.12.7 · released 2026-05-06 · [advisory](https://access.redhat.com/errata/RHSA-2026:14276)
- **RHSA-2026:14272** · Red Hat · fixed in: Red Hat AMQ Broker 7.13.5 · released 2026-05-06 · [advisory](https://access.redhat.com/errata/RHSA-2026:14272)
- **RHSA-2026:8509** · Red Hat · fixed in: Red Hat AMQ Broker 7.14.0 · released 2026-04-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:8509)
- **RHSA-2026:70421** · Red Hat · fixed in: Red Hat JBoss Enterprise Application Platform 6.0.7.GA · released 2026-09-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:70421)
- **RHSA-2026:10184** · Red Hat · fixed in: Red Hat OpenShift AI 2.25 · released 2026-04-23 · [advisory](https://access.redhat.com/errata/RHSA-2026:10184)
- **RHSA-2026:34608** · Red Hat · fixed in: Streams for Apache Kafka 2.9.4 · released 2026-07-02 · [advisory](https://access.redhat.com/errata/RHSA-2026:34608)
- **Red Hat VEX** · Important · affected: Red Hat build of Debezium 2, Red Hat build of Debezium 3, Red Hat Fuse 7, Red Hat JBoss Enterprise Application Platform Expansion Pack, Red Hat Offline Knowledge Portal, Red Hat OpenShift AI (RHOAI), … · no fix planned: Red Hat build of Debezium 2, Red Hat build of Debezium 3, Red Hat Fuse 7, streams for Apache Kafka 3, … · updated 2026-09-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-24281.json)