org.keycloak:keycloak-common@26.0.5 vulnerabilities

org.keycloak:keycloak-common is an Open Source Identity and Access Management For Modern Applications and Services.

Affected versions of this package are vulnerable to HTTP Request Smuggling due to improper handling of proxy headers resulting in costly DNS resolution operations. An attacker could tie up IO threads and potentially cause a denial of service by exploiting these operations.

Notes:

1. This is only exploitable if the attacker has 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.

2. For versions 26.x, this is only exploitable if the realm must have SslRequired=EXTERNAL (the default), HTTP must be enabled, the instance must not be using a full hostname URL, access must come from behind a proxy (assuming the proxy overwrites the X-Forwarded-For header), and trusted proxies must not be set or must incorrectly trust the client from which the request is originating.

Upgrade org.keycloak:keycloak-common to version 26.0.6 or higher.