CVE-2026-3872 Keycloak: keycloak: information disclosure due to redirect_uri validation bypass
Attackers can bypass redirect URI validation to steal access tokens, leading to information disclosure and potential account takeover in Keycloak deployments.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-3872?
CVE-2026-3872 is a high-severity vulnerability in Redhat Build of Keycloak, published on 2 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
A flaw was found in Keycloak. This issue allows an attacker, who controls another path on the same web server, to bypass the allowed path in redirect Uniform Resource Identifiers (URIs) that use a wildcard. A successful attack may lead to the theft of an access token, resulting in information disclosure.
Weakness: CWE-601
Which versions are affected by CVE-2026-3872?
3 open source packages ship an affected version, including org.keycloak:keycloak-services and keycloak. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
org.keycloak:keycloak-services Maven | All versions | 26.5.7 |
org.keycloak:keycloak-services Maven | All versions | 26.5.7 |
keycloak Bitnami | From 26.2.0 | 26.2.1, 26.3.0, 26.4.1, 26.5.0 |
Products include Redhat Build of Keycloak.
How do I fix CVE-2026-3872?
Upgrade org.keycloak:keycloak-services to 26.5.7 or later.
Is CVE-2026-3872 being exploited?
There is no known exploitation of CVE-2026-3872 in the wild and no public exploit code.
Other vulnerabilities in Redhat Build of Keycloak
- CVE-2026-15572 Keycloak-services: keycloak-services: dcr protocol mapper type-swap policy bypass allows privilege escalation
- CVE-2026-3047 Keycloak SAML Broken has Authentication Bypass by Primary Weakness
- CVE-2026-15573 Keycloak-services: keycloak-services: authorization bypass via unnormalized uri matching in pathmatcher
- CVE-2026-16102 Keycloak-services: keycloak-services: default dcr policy allows role forgery via user property mappers
- CVE-2026-1609 Org.keycloak/keycloak-quarkus-server: keycloak: unauthorized access via jwt authorization grant with disabled users
Sources
Also known as BIT-keycloak-2026-3872, ECHO-cc7d-8394-7880, GHSA-cjm2-j6cm-6p6m, MINI-69xr-mhqw-p2m5, MINI-8f53-4v69-q7cx.