Vulnerability in Keycloak Core Services Affects Security of Client Configurations
CVE-2026-18211

4.2MEDIUM

Key Information:

Vendor

Red Hat
Status
Red Hat Build Of Keycloak
Red Hat Data Grid 8
Red Hat Jboss Enterprise Application Platform Expansion Pack
Red Hat Single Sign-on 7
Vendor
CVE Published:
31 July 2026

What is CVE-2026-18211?

A flaw in the client policy executor of Keycloak core services allows attackers to bypass security measures for client configurations. This component enforces essential requirements, such as the need for encrypted connections for redirect URIs. However, due to an inadequate validation process that solely examines the beginning of a web address, attackers can exploit this weakness using a specially crafted domain name. This vulnerability poses a risk of intercepted sensitive authentication codes, as it may redirect unencrypted connections to malicious domains.

References

https://access.redhat.com/security/cve/CVE-2026-18211
vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2508306
issue-trackingx_refsource_REDHAT

CVSS V3.1

Score:
4.2
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
Low
Availability:
Low
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Red Hat would like to thank Paul Bottinelli (Trail of Bits) for reporting this issue.
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