CVE-2026-24281CWE-295CWE-350

Apache ZooKeeper: Reverse-DNS fallback enables hostname verification bypass in ZooKeeper ZKTrustManager

Medium · published March 7, 2026

CVSS v3.1
5.9
EPSS
1%
Percentile
50.3
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.9 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00645 · 50.3th percentile
Weaknesses
CWE-295 · Improper Certificate Validation; CWE-350 · Reliance on Reverse DNS Resolution for a Security-Critical Action
Published
2026-03-07T08:50Z
EPSS history
Timeline
  • 07 MAR 08:50Z
    Apache ZooKeeper: Reverse-DNS fallback enables hostname verification bypass in ZooKeeper ZKTrustManager
    cvelistv5