{"id":"CVE-2021-23937","aliases":["GHSA-hmhg-95wh-r699"],"url":"https://o3.security/vulnerability/CVE-2021-23937","summary":"DNS based denial of service in Apache Wicket","details":"A DNS proxy and possible amplification attack vulnerability in WebClientInfo of Apache Wicket allows an attacker to trigger arbitrary DNS lookups from the server when the X-Forwarded-For header is not properly sanitized. This DNS lookup can be engineered to overload an internal DNS server or to slow down request processing of the Apache Wicket application causing a possible denial of service on either the internal infrastructure or the web application itself. This issue affects Apache Wicket Apache Wicket 9.x version 9.2.0 and prior versions; Apache Wicket 8.x version 8.11.0 and prior versions; Apache Wicket 7.x version 7.17.0 and prior versions and Apache Wicket 6.x version 6.2.0 and later versions.","published":"2021-05-25T17:15:08.187Z","modified":"2026-07-09T00:12:52.300490Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Maven","name":"org.apache.wicket:wicket-core","fixedVersion":"9.3.0"},{"ecosystem":"Maven","name":"org.apache.wicket:wicket-core","fixedVersion":"8.12.0"},{"ecosystem":"Maven","name":"org.apache.wicket:wicket-core","fixedVersion":"7.18.0"}],"fix":null,"references":[{"type":"WEB","url":"https://lists.apache.org/thread.html/r127c0c1f3cb71e5bc619ad1e4b898b97c49758d1f20a54042966473e%40%3Cannounce.wicket.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/r127c0c1f3cb71e5bc619ad1e4b898b97c49758d1f20a54042966473e%40%3Cusers.wicket.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/r8ccbd91b56ebf045d151bd4282bfeea7842a0698a0b76118fca8fe78%40%3Cdev.wicket.apache.org%3E"},{"type":"ADVISORY","url":"https://lists.apache.org/thread.html/rc2ef22f90793e158cef65a7e370cdbca023c499d1403d65feeca870d%40%3Cusers.wicket.apache.org%3E"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-09T00:12:52.300490Z"}}