CVE-2026-4874: A flaw was found in Keycloak. An authenticated attacker can perform Server-Side Request Forgery (SSRF) by manipulating the `client_session_host` param...

Description

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.

Metrics

CVSS 3.1

3.1/10

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

EPSS Probability

0.29%

21.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-918

Affected Software

Vendor	Product	Versions
Redhat	Build Of Keycloak	All versions
Redhat	Jboss Enterprise Application Platform	8.0.0
Redhat	Jboss Enterprise Application Platform Expansion Pack	All versions
Redhat	Single Sign-On	7.0

References

Timeline

Published: Mar 26, 2026
Last Modified: Jun 26, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2026-4874?

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.

How severe is CVE-2026-4874?

CVE-2026-4874 has a CVSS score of 3.1/10 (LOW severity). The EPSS model estimates a 0.29% probability of exploitation in the next 30 days.

How do I fix CVE-2026-4874?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.