{"id":"UBUNTU-CVE-2026-24281","details":"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.","modified":"2026-06-30T18:16:27.707965226Z","published":"2026-03-07T09:16:00Z","upstream":["CVE-2026-24281"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-24281"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-24281"},{"type":"REPORT","url":"https://lists.apache.org/thread/088ddsbrzhd5lxzbqf5n24yg0mwh9jt2"},{"type":"REPORT","url":"http://www.openwall.com/lists/oss-security/2026/03/07/4"}],"affected":[{"package":{"name":"zookeeper","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/zookeeper?arch=source&distro=esm-infra-legacy%2Ftrusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.4.5+dfsg-1","3.4.5+dfsg-1ubuntu0.1~esm1","3.4.5+dfsg-1ubuntu0.1~esm3"],"ecosystem_specific":{"binaries":[{"binary_name":"libzookeeper-java","binary_version":"3.4.5+dfsg-1ubuntu0.1~esm3"},{"binary_name":"libzookeeper-mt2","binary_version":"3.4.5+dfsg-1ubuntu0.1~esm3"},{"binary_version":"3.4.5+dfsg-1ubuntu0.1~esm3","binary_name":"libzookeeper-st2"},{"binary_version":"3.4.5+dfsg-1ubuntu0.1~esm3","binary_name":"libzookeeper2"},{"binary_name":"python-zookeeper","binary_version":"3.4.5+dfsg-1ubuntu0.1~esm3"},{"binary_name":"zookeeper","binary_version":"3.4.5+dfsg-1ubuntu0.1~esm3"},{"binary_name":"zookeeper-bin","binary_version":"3.4.5+dfsg-1ubuntu0.1~esm3"},{"binary_name":"zookeeperd","binary_version":"3.4.5+dfsg-1ubuntu0.1~esm3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-24281.json"}},{"package":{"name":"zookeeper","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/zookeeper?arch=source&distro=esm-apps%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.4.6-8","3.4.7-1","3.4.8-1","3.4.8-1ubuntu0.1~esm1","3.4.8-1ubuntu0.1~esm2"],"ecosystem_specific":{"binaries":[{"binary_version":"3.4.8-1ubuntu0.1~esm2","binary_name":"libzookeeper-java"},{"binary_version":"3.4.8-1ubuntu0.1~esm2","binary_name":"libzookeeper-mt2"},{"binary_name":"libzookeeper-st2","binary_version":"3.4.8-1ubuntu0.1~esm2"},{"binary_name":"libzookeeper2","binary_version":"3.4.8-1ubuntu0.1~esm2"},{"binary_name":"python-zookeeper","binary_version":"3.4.8-1ubuntu0.1~esm2"},{"binary_name":"zookeeper","binary_version":"3.4.8-1ubuntu0.1~esm2"},{"binary_version":"3.4.8-1ubuntu0.1~esm2","binary_name":"zookeeper-bin"},{"binary_name":"zookeeperd","binary_version":"3.4.8-1ubuntu0.1~esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-24281.json"}},{"package":{"name":"zookeeper","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/zookeeper?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.4.10-2","3.4.10-3","3.4.13-3","3.4.13-3ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libzookeeper-java","binary_version":"3.4.13-3ubuntu0.1~esm1"},{"binary_name":"libzookeeper-mt2","binary_version":"3.4.13-3ubuntu0.1~esm1"},{"binary_name":"libzookeeper-st2","binary_version":"3.4.13-3ubuntu0.1~esm1"},{"binary_name":"python-zookeeper","binary_version":"3.4.13-3ubuntu0.1~esm1"},{"binary_name":"zookeeper","binary_version":"3.4.13-3ubuntu0.1~esm1"},{"binary_name":"zookeeper-bin","binary_version":"3.4.13-3ubuntu0.1~esm1"},{"binary_name":"zookeeperd","binary_version":"3.4.13-3ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-24281.json"}},{"package":{"name":"zookeeper","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/zookeeper?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.4.13-1","3.4.13-3","3.4.13-3build1","3.4.13-4","3.4.13-5","3.4.13-5build1","3.4.13-5ubuntu0.1"],"ecosystem_specific":{"binaries":[{"binary_name":"libzookeeper-java","binary_version":"3.4.13-5ubuntu0.1"},{"binary_name":"libzookeeper-mt2","binary_version":"3.4.13-5ubuntu0.1"},{"binary_name":"libzookeeper-st2","binary_version":"3.4.13-5ubuntu0.1"},{"binary_name":"python3-zookeeper","binary_version":"3.4.13-5ubuntu0.1"},{"binary_name":"zookeeper","binary_version":"3.4.13-5ubuntu0.1"},{"binary_name":"zookeeper-bin","binary_version":"3.4.13-5ubuntu0.1"},{"binary_name":"zookeeperd","binary_version":"3.4.13-5ubuntu0.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-24281.json"}},{"package":{"name":"zookeeper","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/zookeeper?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.4.13-5ubuntu4","3.4.13-6ubuntu2","3.4.13-6ubuntu3","3.4.13-6ubuntu4","3.4.13-6ubuntu4.1"],"ecosystem_specific":{"binaries":[{"binary_name":"libzookeeper-java","binary_version":"3.4.13-6ubuntu4.1"},{"binary_version":"3.4.13-6ubuntu4.1","binary_name":"libzookeep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