CVE-2026-4874
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.
Statement
This flaw allows an authenticated attacker to perform Server-Side Request Forgery (SSRF) by manipulating the client_session_host parameter during refresh token requests. This vulnerability is exploitable when a Keycloak client is configured to use the backchannel.logout.url with the application.session.host placeholder, enabling the attacker to probe internal networks from the Keycloak server's context. Exploitation requires valid user credentials and a logout event.
Mitigation
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 3.1 | 3.1 | 3.1 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | High | High |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | Low | Low | Low |
| Integrity Impact | None | None | None |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
NVD: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
Acknowledgements
Red Hat would like to thank Evan Hendra (Independent Security Researcher) for reporting this issue.
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