The following advisory data is extracted from:
https://access.redhat.com/security/data/csaf/v2/advisories/2023/rhsa-2023_7858.json
Red Hat officially shut down their mailing list notifications October 10, 2023.  Due to this, Packet Storm has recreated the below data as a reference point to raise awareness.  It must be noted that due to an inability to easily track revision updates without crawling Red Hat's archive, these advisories are single notifications and we strongly suggest that you visit the Red Hat provided links to ensure you have the latest information available if the subject matter listed pertains to your environment.
- Packet Storm Staff
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Red Hat Security Advisory
Synopsis:           Important: Red Hat Single Sign-On 7.6.6 security update
Advisory ID:        RHSA-2023:7858-03
Product:            Red Hat Single Sign-On
Advisory URL:       https://access.redhat.com/errata/RHSA-2023:7858
Issue date:         2023-12-14
Revision:           03
CVE Names:          CVE-2023-6134
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Summary: 
A security update is now available for Red Hat Single Sign-On 7.6 from the Customer Portal.
Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.
Description:
Red Hat Single Sign-On 7.6 is a standalone server, based on the Keycloak project, that provides authentication and standards-based single sign-on capabilities for web and mobile applications.
This release of Red Hat Single Sign-On 7.6.6 serves as a replacement for Red Hat Single Sign-On 7.6.5, and includes bug fixes and enhancements.
Security Fix(es):
* keycloak: redirect_uri validation logic that allows for a bypass of otherwise explicitly allowed hosts (CVE-2023-6134)
* keycloak: reflected XSS via wildcard in OIDC redirect_uri (CVE-2023-6291)
* keycloak: offline session token DoS (CVE-2023-6563)
For more details about the security issue(s), including the impact, a CVSS score, and other related information, refer to the CVE page(s) listed in the References section.
Solution:
CVEs:
CVE-2023-6134
References:
https://access.redhat.com/security/updates/classification/#important
https://access.redhat.com/jbossnetwork/restricted/listSoftware.html?product=core.service.rhsso&downloadType=patches&version=7.6
https://bugzilla.redhat.com/show_bug.cgi?id=2249673
https://bugzilla.redhat.com/show_bug.cgi?id=2251407
https://bugzilla.redhat.com/show_bug.cgi?id=2253308