CVE-2021-23937: DNS proxy and possible amplification attack

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 4.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-05-25 · updated 2026-06-17
Weakness: CWE-200

Description

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 Software Foundation Apache Wicket: from 6.0.0 through 6.2.0; from 7.0.0 through 7.17.0; from 8.0.0 through 8.11.0; from 9.0.0 through 9.2.0

References

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