CVE-2026-24281
Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP…
Technology
Apache ZooKeeper
CVSS Score
7.4 / 10.0
Affected Versions
>=3.8.0 <3.8.6; >=3.9.0 <3.9.5
Upstream Fix
See upstream advisory
Published
March 7, 2026
OSSeva Coverage
Fixed upstream
Description
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.
Is your Apache ZooKeeper deployment affected?
If you're running >=3.8.0 <3.8.6; >=3.9.0 <3.9.5, you need this patch. Book a discovery call to get covered.