CVE-2021-23937: Apache Wicket

High severity, CVSS 7.5. EPSS: 4.3% chance of exploitation in the next 30 days.

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.

Affected products

• Apache Wicket: from 6.0.0, up to and including 6.2.0; from 7.0.0, up to and including 7.17.0; from 8.0.0, up to and including 8.11.0; from 9.0.0, up to and including 9.2.0

Published 2021-05-25. Last modified 2026-06-17.