{"id":"CVE-2017-5637","url":"https://www.cyber-defence.io/tools/cve/CVE-2017-5637","generatedAt":"2026-10-28T22:08:03.185Z","title":"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.","description":"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.","published":"2017-10-10T01:30:22.000Z","lastModified":"2026-06-17T01:20:54.000Z","status":"Modified","sourceIdentifier":"security@apache.org","cvss":{"version":"3.0","score":7.5,"severity":"HIGH","vector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-306","CWE-400"],"affected":["apache/zookeeper","debian/debian linux"],"epss":{"score":0.73064,"percentile":0.99453,"date":"2026-10-27","history":[{"date":"2026-09-21","score":0.68529,"percentile":0.99327},{"date":"2026-09-22","score":0.73064,"percentile":0.99431}]},"kev":{"listed":false},"exploits":{"count":1,"verified":false,"firstPublished":"2017-07-02","source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[{"edbId":42294,"kind":"exploit","title":"Zookeeper 3.5.2 Client - Denial of Service","url":"https://www.exploit-db.com/exploits/42294","sourceUrl":"https://gitlab.com/exploit-database/exploitdb/-/blob/main/exploits/multiple/dos/42294.py","file":"exploits/multiple/dos/42294.py","published":"2017-07-02","added":"2017-07-04","updated":"2017-10-04","author":"Brandon Dennis","type":"dos","platform":"multiple","port":2181,"verified":false,"codes":["CVE-2017-5637"],"tags":null,"aliases":null,"applicationUrl":null,"screenshotUrl":null,"referenceUrl":null}]},"verdict":{"level":"urgent","text":"EPSS puts the probability of exploitation in the next 30 days at 73.1%, higher than 99% of all known CVEs. Patch or mitigate before the next change window."},"changes":[],"references":[{"url":"http://www.debian.org/security/2017/dsa-3871","tags":["Third Party Advisory"],"source":"security@apache.org"},{"url":"http://www.securityfocus.com/bid/98814","tags":["Third Party Advisory","VDB Entry"],"source":"security@apache.org"},{"url":"https://access.redhat.com/errata/RHSA-2017:2477","source":"security@apache.org"},{"url":"https://access.redhat.com/errata/RHSA-2017:3354","source":"security@apache.org"},{"url":"https://access.redhat.com/errata/RHSA-2017:3355","source":"security@apache.org"},{"url":"https://issues.apache.org/jira/browse/ZOOKEEPER-2693","tags":["Issue Tracking","Mitigation","Vendor Advisory"],"source":"security@apache.org"},{"url":"https://lists.apache.org/thread.html/053d9ce4d579b02203db18545fee5e33f35f2932885459b74d1e4272%40%3Cissues.activemq.apache.org%3E","source":"security@apache.org"},{"url":"https://lists.apache.org/thread.html/58170aeb7a681d462b7fa31cae81110cbb749d2dc83c5736a0bb8370%40%3Cdev.zookeeper.apache.org%3E","source":"security@apache.org"},{"url":"https://lists.apache.org/thread.html/bcce5a9c532b386c68dab2f6b3ce8b0cc9b950ec551766e76391caa3%40%3Ccommits.nifi.apache.org%3E","source":"security@apache.org"},{"url":"https://lists.apache.org/thread.html/rca37935d661f4689cb4119f1b3b224413b22be161b678e6e6ce0c69b%40%3Ccommits.nifi.apache.org%3E","source":"security@apache.org"},{"url":"https://www.oracle.com//security-alerts/cpujul2021.html","source":"security@apache.org"},{"url":"https://www.oracle.com/security-alerts/cpujul2020.html","source":"security@apache.org"},{"url":"http://www.debian.org/security/2017/dsa-3871","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.securityfocus.com/bid/98814","tags":["Third Party Advisory","VDB Entry"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2017:2477","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2017:3354","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2017:3355","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://issues.apache.org/jira/browse/ZOOKEEPER-2693","tags":["Issue Tracking","Mitigation","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.apache.org/thread.html/053d9ce4d579b02203db18545fee5e33f35f2932885459b74d1e4272%40%3Cissues.activemq.apache.org%3E","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.apache.org/thread.html/58170aeb7a681d462b7fa31cae81110cbb749d2dc83c5736a0bb8370%40%3Cdev.zookeeper.apache.org%3E","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.apache.org/thread.html/bcce5a9c532b386c68dab2f6b3ce8b0cc9b950ec551766e76391caa3%40%3Ccommits.nifi.apache.org%3E","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.apache.org/thread.html/rca37935d661f4689cb4119f1b3b224413b22be161b678e6e6ce0c69b%40%3Ccommits.nifi.apache.org%3E","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.oracle.com//security-alerts/cpujul2021.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.oracle.com/security-alerts/cpujul2020.html","source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2017-5637","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}