Answer in brief
CVE-2026-18211 records a Medium severity (CVSS 4.2) vulnerability in Keycloak-services: keycloak-services: secure-client-uris policy bypass via localhost-prefixed domains. The current sources do not mark it as known exploited. Affected software not mapped in the current feed; confirm the named product and version against your inventory.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 4.2. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
Affected software not mapped in the current feed; confirm the named product and version against your inventory.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:redhat:build_of_keycloak:-:*:*:*:-:*:*:* | Not reported | Not reported |
Published upstream
Jul 31, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 31, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 3, 2026
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.
Quoted source text, attributed separately from HOL analysis.