CVE-2026-1518
Server-Side Request Forgery in Keycloak CIBA Backchannel Endpoint
Publication date: 2026-02-02
Last updated on: 2026-02-02
Assigner: Red Hat, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| redhat | keycloak | * |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| 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. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability in Keycloak's CIBA feature involves insufficient validation of the backchannel notification endpoint configured by clients. An attacker with high privileges (Administrator or valid Initial Access Token) can set this endpoint to arbitrary internal URLs, causing Keycloak to send blind POST requests to these internal services during CIBA authentication in ping mode. This is a Blind Server-Side Request Forgery (SSRF) that allows influencing server-side network interactions without seeing the response. [1]
How can this vulnerability impact me? :
The vulnerability allows an attacker with high privileges to make Keycloak send blind POST requests to internal services, including localhost or cloud metadata endpoints. This can lead to abuse of internal services and potentially expose internal network resources to unauthorized interactions. However, exploitation requires privileged access, and the severity is considered low. [1]
How can this vulnerability be detected on my network or system? Can you suggest some commands?
Detection involves monitoring for unusual or unauthorized changes to the backchannel_client_notification_endpoint configuration in Keycloak, especially by users with Administrator access or possessing Initial Access Tokens. Additionally, network monitoring for unexpected outbound POST requests from the Keycloak server to internal URLs or cloud metadata service endpoints can help identify exploitation attempts. Specific commands are not provided in the resources. [1]
What immediate steps should I take to mitigate this vulnerability?
Immediate mitigation steps include restricting Administrator access and Initial Access Tokens to trusted users only, reviewing and validating the backchannel_client_notification_endpoint configurations to ensure they do not point to internal or sensitive URLs, and monitoring Keycloak logs and network traffic for suspicious POST requests to internal endpoints. Applying any available patches or updates from Keycloak addressing this issue is also recommended. [1]
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
[{'type': 'paragraph', 'content': "The vulnerability in Keycloak's CIBA feature allows an attacker with high privileges to cause blind server-side requests to internal services by configuring backchannel notification endpoints without sufficient validation."}, {'type': 'paragraph', 'content': 'While this flaw could potentially be used to influence internal network interactions, there is no direct indication from the provided information that it leads to unauthorized disclosure or modification of personal or sensitive data.'}, {'type': 'paragraph', 'content': 'Given the low severity score and the requirement for privileged access to exploit, the impact on compliance with standards like GDPR or HIPAA is likely limited, but organizations should consider the risk of internal service abuse and ensure proper access controls and monitoring are in place.'}] [1]