Red Hat Security Advisory: Red Hat build of Keycloak 26.4.17 Security Update

🔗 CVE IDs covered (38)

📋 Description

🎯 Affected products1

• Red Hat build of Keycloak 26.4.17

✅ Remediation

Before applying the update, back up your existing installation, including all applications, configuration files, databases and database settings, and so on. Workaround: Enforce strict DigestInfo encoding checks requiring explicit ASN.1 NULL parameters in RSA PKCS#1 v1.5 signature verification, or mandate the use of RSA-PSS signature schemes in application TLS/crypto configuration. Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. Workaround: Limit the maximum string length of incoming X.500 distinguished names at application or API gateway boundaries, or restrict the acceptance of unauthenticated client certificates containing complex distinguished names. Workaround: To mitigate this issue, ensure that application-layer certificate verification is implemented for services utilizing Netty with mutual TLS. This provides an additional layer of authentication beyond the TLS handshake, preventing unauthorized access even if the SNI routing is bypassed and a less restrictive default SslContext is used. Workaround: To mitigate this vulnerability, applications using Hibernate ORM should avoid passing untrusted user-controlled input directly as JSON path arguments to `json_query`, `json_exists`, or `json_value` functions. If dynamic JSON querying is necessary, strictly validate or whitelist the JSON path input against a predefined pattern (e.g., allowing only alphanumeric characters and dots) before use. Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. --- CME Mitigation Guidance (2026-11-06) --- Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure. The highest-value action is to enforce XML payload size and element count validation during SAML SOAP request parsing before DOM tree construction: upgrade to Red Hat build of Keycloak 26.4.17, 26.6.8 (or the corresponding fixed Red Hat builds), which enforce XML payload size and element count limits when parsing incoming SAML SOAP requests, closing all 2 injection vectors (SAML Artifact Resolution SOAP requests with large or deeply nested XML payloads, SAML ECP SOAP requests containing millions of empty XML elements). Until patched, this is a concern on Keycloak deployments exposing SAML SOAP endpoints to unauthenticated network access, so Restrict network access to SAML SOAP endpoints such as /realms/{realm}/protocol/saml/resolve to trusted internal clients and reverse proxies. As a compensating measure, Configure systemd service watchdog and automatic restart directives to detect OutOfMemoryError process exits and restore Keycloak service availability and Implement rate limiting and connection throttling on SOAP requests targeting the SAML resolve endpoint to mitigate rapid heap exhaustion. These controls limit blast radius and contain exploitation, but they do not fix the underlying unbounded XML parsing defect — apply the upstream patch to fully remediate. Highest-impact CME: CME-1204 Service Watchdog and Automatic Restart (systemd WatchdogSec/Restart) (medium) Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. --- CME Mitigation Guidance (2026-11-06) --- Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure. The highest-value action is to enforce proof of possession for bound keys in SAML identity broker subject-confirmation validation: upgrade to Keycloak 26.4.17 / 26.6.8 (or the corresponding fixed Red Hat builds), which enforce proof of possession for the bound key or reject assertions that contain only unvalidated holder-of-key confirmations, closing replaying intercepted SAML holder-of-key assertions. Until patched, this is a concern on Keycloak deployments configured as a SAML identity broker trusting upstream providers that issue holder-of-key assertions, so restrict and audit trusted upstream SAML identity providers issuing holder-of-key assertions to prevent interception and unauthorized replay of signed assertions. As a compensating measure, enforce mandatory secondary authentication factor in Keycloak post-federation to block login completion on replayed assertions. These controls limit blast radius and contain exploitation, but they do not fix the underlying missing proof-of-possession verification flaw — apply the upstream patch to fully remediate. Highest-impact CME: CME-801 Multi-Factor Authentication (MFA) (medium) Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. --- CME Mitigation Guidance (2026-11-06) --- Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure. The highest-value action is to validate protocol mapper claim.name configurations during Dynamic Client Registration to deny mapping to reserved identity claims: upgrade to Red Hat build of Keycloak 26.4.17, 26.6.8 (or the corresponding fixed Red Hat builds), which validate and reject protocol mapper configurations in Dynamic Client Registration that assign reserved claims to claim.name, closing all 2 injection vectors (Dynamic Client Registration protocol mapper configuration mapping user profile attributes to the sub claim, Dynamic Client Registration protocol mapper configuration mapping user profile attributes to the aud claim). Until patched, this is a concern on Keycloak deployments enabling Dynamic Client Registration where users possess an Initial Access Token and editable realm profile attributes, so restrict issuance of Initial Access Tokens, monitor new client registrations, and restrict user capabilities to edit profile attributes. As a compensating measure, detect unauthorized Dynamic Client Registration creations and protocol mapper changes by alerting on configuration drift against declared realm baselines and log Dynamic Client Registration events and mapper configurations to a SIEM to identify unauthorized clients mapping reserved token claims. These controls limit blast radius and contain exploitation, but they do not fix the underlying unvalidated protocol mapper claim.name defect — apply the upstream patch to fully remediate. Highest-impact CME: CME-1315 Allowlist-Preferred Input Validation (Deny-by-Default Filtering) (high) Workaround: See https://github.com/netty/netty/security/advisories/GHSA-2g37-3h88-55hc for fixed versions and remediation guidance. Workaround: See https://github.com/netty/netty/security/advisories/GHSA-hcvj-94mj-jp5c for fixed versions and remediation guidance. Workaround: See https://github.com/netty/netty/security/advisories/GHSA-j58c-g352-8h4p for fi…

🔗 References (3)

• selfhttps://access.redhat.com/errata/RHSA-2026:95759
• externalhttps://access.redhat.com/security/updates/classification/#important
• selfhttps://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_95759.json