Red Hat Keycloak Refresh Token client_session_host server-side request forgery

Summaryinfo

A vulnerability classified as critical was found in Red Hat Keycloak. This affects an unknown function of the component Refresh Token Handler. Such manipulation of the argument client_session_host leads to server-side request forgery. This vulnerability is referenced as CVE-2026-4874. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in Red Hat Keycloak (version unknown) and classified as critical. Affected by this issue is an unknown function of the component Refresh Token Handler. The manipulation of the argument client_session_host with an unknown input leads to a server-side request forgery vulnerability. Using CWE to declare the problem leads to CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. Impacted is confidentiality, integrity, and availability. CVE summarizes:

A flaw was found in Keycloak. An authenticated attacker can perform Server-Side Request Forgery (SSRF) by manipulating the `client_session_host` parameter during refresh token requests. This occurs when a Keycloak client is configured to use the `backchannel.logout.url` with the `application.session.host` placeholder. Successful exploitation allows the attacker to make HTTP requests from the Keycloak server’s network context, potentially probing internal networks or internal APIs, leading to information disclosure.

The advisory is available at access.redhat.com. This vulnerability is handled as CVE-2026-4874 since 03/26/2026. The exploitation is known to be difficult. The attack may be launched remotely. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 06/10/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

• Red Hat

Name

• Keycloak

License

• open-source

Website

• Vendor: https://www.redhat.com/

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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