CVE-2017-5637: Apache Zookeeper

High severity, CVSS 7.5. EPSS: 73.1% chance of exploitation in the next 30 days.

Two four letter word commands "wchp/wchc" are CPU intensive and could cause spike of CPU utilization on Apache ZooKeeper server if abused, which leads to the server unable to serve legitimate client requests. Apache ZooKeeper thru version 3.4.9 and 3.5.2 suffer from this issue, fixed in 3.4.10, 3.5.3, and later.

Affected products

• Apache Zookeeper: version 3.4.0 only; version 3.4.1 only; version 3.4.2 only; version 3.4.3 only; version 3.4.4 only; version 3.4.5 only; …
• Debian Debian Linux: version 8.0 only

Published 2017-10-10. Last modified 2026-06-17.