Duplicate Advisory: Keycloak proxy header handling Denial-of-Service (DoS) vulnerability

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-jgwc-jh89-rpgq. This link is maintained to preserve external references.

Original Description

A vulnerability was found in the Keycloak Server. The Keycloak Server is vulnerable to a denial of service (DoS) attack due to improper handling of proxy headers. When Keycloak is configured to accept incoming proxy headers, it may accept non-IP values, such as obfuscated identifiers, without proper validation. This issue can lead to costly DNS resolution operations, which an attacker could exploit to tie up IO threads and potentially cause a denial of service.
The attacker must have access to send requests to a Keycloak instance that is configured to accept proxy headers, specifically when reverse proxies do not overwrite incoming headers, and Keycloak is configured to trust these headers.