CVE-2026-18217
LowCVSS 3.4Exploitation Probability (EPSS)
Low risk9th percentile - higher than 9% of all known CVEs
Summary
In the SAML protocol implementation of Keycloak, when a client is configured with a wildcard redirect URL, an attacker can craft a request with malicious parameters. After user authentication, Keycloak appends its legitimate response to the attacker's parameters, potentially causing the service provider to process the attacker's data instead of real login information, leading to user login to the wrong account.
Risk Assessment
Users can be logged into the attacker's account, potentially leading to identity theft or unauthorized data access.
Recommendation
Update Keycloak to a version that fixes this vulnerability. Avoid using wildcard redirect URLs in SAML configurations.
Original NVD description (English source)
A flaw was found in the SAML protocol implementation of Keycloak, an open-source identity and access management solution. The issue occurs when Keycloak handles SAML authentication requests using the HTTP-Redirect binding. If a client is configured with a wildcard redirect URL, an attacker can craft a request that includes malicious parameters. When a user authenticates, Keycloak appends its legitimate response to the attacker's parameters. This can cause some service providers to process the attacker's data instead of the real login information, potentially leading to a user being logged into the wrong account.