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Vulnerability record · CVE-2026-18211 · published 31 July 2026

CVE-2026-18211: Redhat build of keycloak improper input validation vulnerability

Redhat · Build Of Keycloak

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.

5.4 CVSS 3.1 Medium EPSS 0.31% · top 78.8% CWE-20 · Improper input validation
5.4CVSS 3.1 base score
0.31%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
7 Aug 2026Last modified by NVD

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

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

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-18211), CISA KEV, FIRST EPSS (scores of 2026-09-30). This page is refreshed as NVD updates the record.