Apache ZooKeeper up to 3.8.5/3.9.4 ZKTrustManager certificate host validation

Summaryinfo

A vulnerability labeled as critical has been found in Apache ZooKeeper up to 3.8.5/3.9.4. Impacted is an unknown function of the component ZKTrustManager. Executing a manipulation can lead to certificate host validation. This vulnerability appears as CVE-2026-24281. The attack may be performed from remote. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability has been found in Apache ZooKeeper up to 3.8.5/3.9.4 and classified as problematic. This vulnerability affects an unknown part of the component ZKTrustManager. The manipulation with an unknown input leads to a certificate host validation vulnerability. The CWE definition for the vulnerability is CWE-297. The product communicates with a host that provides a certificate, but the product does not properly ensure that the certificate is actually associated with that host. As an impact it is known to affect integrity. CVE summarizes:

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 advisory is available at lists.apache.org. This vulnerability was named CVE-2026-24281. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 04/09/2026). This vulnerability is assigned to T1587.003 by the MITRE ATT&CK project.

Upgrading to version 3.8.6 or 3.9.5 eliminates this vulnerability.

The vulnerability is also documented in the databases at EUVD (EUVD-2026-10139) and CERT Bund (WID-SEC-2026-1032). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• IBM Tivoli Network Manager

Productinfo

Vendor

• Apache

Name

• ZooKeeper

Version

• 3.8.0
• 3.8.1
• 3.8.2
• 3.8.3
• 3.8.4
• 3.8.5
• 3.9.0
• 3.9.1
• 3.9.2
• 3.9.3
• 3.9.4

License

• open-source

Website

• Vendor: https://www.apache.org/

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Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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