CVE-2026-118425
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Keycloak Loopback Address Bypass via DNS Resolution

Publication date: 2026-10-29

Last updated on: 2026-10-29

Assigner: redhat-SADP

Description
A flaw was found in the secure-redirect-uris-enforcer client policy of Keycloak, an identity and access management solution. The issue occurs when the policy is configured to allow loopback addresses, as Keycloak resolves hostnames via DNS during validation. An attacker can bypass domain allowlist restrictions by using a hostname that resolves to a loopback address, potentially allowing the registration of unauthorized redirect URIs.

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Meta Information

Published
2026-10-29
Last Modified
2026-10-29
Generated
2026-10-29
AI Q&A
2026-10-29
EPSS Evaluated
N/A
NVD
CVE-2026-118425
EUVD
EUVD-2026-112916

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
Red Hat Red Hat Build of Keycloak *

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-601 The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.

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Executive Summary

This vulnerability is in Keycloak's secure-redirect-uris-enforcer client policy. It allows attackers to bypass domain allowlist restrictions by using hostnames that resolve to loopback addresses. Keycloak resolves hostnames via DNS during validation, enabling unauthorized redirect URI registrations.

Detection Guidance

To detect this vulnerability, check Keycloak server logs for redirect URI validation failures or unusual DNS resolution patterns. Look for client policies configured to allow loopback addresses. No specific commands are provided in the resources, but monitor for DNS queries resolving to 127.0.0.1 or ::1 during redirect URI validation.

Impact Analysis

An attacker could exploit this to register malicious redirect URIs, potentially leading to phishing attacks, session hijacking, or unauthorized access to user data. The impact includes high risks to confidentiality and integrity of data.

Compliance Impact

This vulnerability could lead to unauthorized data access or redirection, violating compliance requirements for data protection and access control in standards like GDPR and HIPAA. It undermines secure authentication and authorization mechanisms.

Mitigation Strategies

Immediate mitigation steps include disabling loopback address allowlist in Keycloak client policies and ensuring DNS resolution does not resolve external hostnames to loopback addresses. Upgrade to a patched version if available. No official mitigation meets Red Hat's criteria currently.

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