CVE-2026-18217

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. Limited direct impact.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-07-31 08:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-08-07 18:05 UTC Last updatedMost recent change to the record

Details

Published

2026-07-31 08:16 UTC

Last modified

2026-08-07 18:05 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-20 · Improper input validation

Record status

Analyzed

Affected

• Redhat Build Of Keycloak

Attack profile CVSS 3.1 · 3.4

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

Required

Scope

Changed

Confidentiality

None

Integrity

Low

Availability

None