Medium [CVE-2026-15943] OIDC IdP update reuses masked client secret after token URL change

A flaw was found in the Keycloak keycloak-services component, which handles the management of identity providers. The issue occurs when a delegated administrator updates an OIDC identity provider using a masked client secret sentinel value.

Due to improper validation, Keycloak reuses the existing real secret even if security-sensitive fields like the token URL have been changed, allowing an attacker to redirect and capture the secret. The Red Hat Product Security team has assessed the severity of this vulnerability as Moderate, given that it requires high administrative privileges to exploit.

Successful exploitation allows an attacker to rebind and capture an OIDC client secret by modifying identity provider configuration fields. The vulnerability's root cause is the unconditional reuse of masked secrets during configuration updates without verifying if sensitive endpoint fields have changed.

Weakness: CWE-1288. Affected Red Hat products: Red Hat Build of Keycloak.

Red Hat lists Red Hat Data Grid 8; Red Hat JBoss Enterprise Application Platform Expansion Pack; Red Hat Single Sign-On 7 as not affected. Red Hat does not currently list a fixing RHSA for this CVE.