CVE-2026-18211 — MEDIUM (4.2)

Vulnerability Description

A flaw was found in the secure-client-uris client policy executor within Keycloak core services. This component is responsible for enforcing security requirements on client configurations, such as requiring encrypted connections for redirect URIs. Due to an improper check that only looks at the start of a web address rather than properly verifying the host, an attacker can bypass these security restrictions by using a specially crafted domain name. This could allow an attacker to intercept sensitive authentication codes over unencrypted connections.

CVSS Score

4.2

MEDIUM

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

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

REQUIRED

Scope

UNCHANGED

Confidentiality

LOW

Integrity

LOW

Availability

NONE

Affected Products

Vendor	Product	Versions
Redhat	Build Of Keycloak	-

Related Weaknesses (CWE)

CWE-20

References

https://access.redhat.com/security/cve/CVE-2026-18211Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2508306Issue TrackingVendor Advisory

FAQ

What is CVE-2026-18211?

CVE-2026-18211 is a vulnerability with a CVSS score of 4.2 (MEDIUM). A flaw was found in the secure-client-uris client policy executor within Keycloak core services. This component is responsible for enforcing security requirements on client configurations, such as req...

How severe is CVE-2026-18211?

CVE-2026-18211 has been rated MEDIUM with a CVSS base score of 4.2/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-18211?

Check the references section above for vendor advisories and patch information. Affected products include: Redhat Build Of Keycloak.