CVE-2021-3827 ECP SAML binding bypasses authentication flows

What is CVE-2021-3827?

CVE-2021-3827 is a medium-severity authentication bypass vulnerability in Redhat Keycloak, published on 23 Aug 2022. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

A flaw was found in keycloak, where the default ECP binding flow allows other authentication flows to be bypassed. By exploiting this behavior, an attacker can bypass the MFA authentication by sending a SOAP request with an AuthnRequest and Authorization header with the user's credentials. The highest threat from this vulnerability is to confidentiality and integrity.

Weakness: CWE-287

Which versions are affected by CVE-2021-3827?

2 open source packages ship an affected version, including org.keycloak:keycloak-saml-core. It affects 3 products.

Products include Redhat Keycloak, Redhat Openshift Container Platform, Redhat Single Sign-On.

How do I fix CVE-2021-3827?

Upgrade org.keycloak:keycloak-saml-core to 18.0.0 or later.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2021-3827 being exploited?

There is no known exploitation of CVE-2021-3827 in the wild and no public exploit code.

Other vulnerabilities in Redhat Keycloak

• CVE-2022-4361 Keycloak vulnerable to cross-site scripting when validating URI-schemes on SAML and OIDC Critical 10.0
• CVE-2022-1245 Keycloak vulnerable to privilege escalation on Token Exchange feature Critical 9.8
• CVE-2021-20195 keycloak Self Stored Cross-site Scripting vulnerability Critical 9.6
• CVE-2019-14910 Keycloak Authentication Error Critical 9.3
• CVE-2019-14909 Keycloak Authentication Error Critical 9.3

All Redhat Keycloak vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-4pc7-vqv5-5r3v.