CVE-2026-18660

A flaw was found in Eclipse Jetty. This vulnerability allows a remote attacker to bypass access controls and reach restricted resources. The issue occurs because the server and proxy components perform case-sensitive validation on host allowlists and denylists. By sending requests with altered character casing in the host name, an attacker can circumvent configured host filtering policies.

This flaw allows an attacker to bypass host-based access control in Eclipse Jetty's server and proxy components. By varying the letter case of the Host header, requests can slip past configured host allow/deny lists, letting an attacker reach resources that virtual-host or proxy filtering was meant to block in affected Red Hat products that use jetty-server or jetty-proxy for this purpose.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

There is no mitigation for this issue other than applying the fix. As a temporary workaround, administrators who rely on Jetty host allow/deny filtering should add case-variant duplicates of every configured hostname to the filter lists, or enforce hostname case-normalization at an upstream load balancer or reverse proxy, until the update is installed.