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Vulnerability · Published Jul 31, 2026 · Assigned by redhat

CVE-2026-18211Keycloak-services: keycloak-services: secure-client-uris policy bypass via localhost-prefixed domains

Medium 4.2

In plain English

A medium-severity improper input validation in Red Hat Build of Keycloak from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities).

Severity (CVSS 3.1)4.2Medium
Exploit odds (30 days)0.3%top 76.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

VendorProductVersions
Red Hat Red Hat Build of Keycloak see references
Red Hat Red Hat Build of Keycloak see references
Red Hat Red Hat Build of Keycloak see references
Red Hat Red Hat Data Grid 8 see references
Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack see references
Red Hat Red Hat Single Sign-On 7 see references

Weakness: CWE-20 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

References