CVE-2021-3754 Keycloak's improper input validation allows using email as username

What is CVE-2021-3754?

CVE-2021-3754 is a medium-severity vulnerability in Redhat Keycloak, published on 26 Aug 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A flaw was found in keycloak where an attacker is able to register himself with the username same as the email ID of any existing user. This may cause trouble in getting password recovery email in case the user forgets the password.

Weakness: CWE-20

Which versions are affected by CVE-2021-3754?

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

Products include Redhat Keycloak, Redhat Single Sign-On.

How do I fix CVE-2021-3754?

Upgrade org.keycloak:keycloak-services to 24.0.1 or later.

Is CVE-2021-3754 being exploited?

There is no known exploitation of CVE-2021-3754 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

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-4vc8-pg5c-vg4x.