What’s Vulnerable › Vulnerabilities

CVE-2021-3827

• Severity: medium (CVSS 6.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2022-08-23 · updated 2026-06-17
• Weakness: CWE-287

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.

Affected products

• Keycloak: before 18.0.0 — fixed in 18.0.0
• Red Hat OpenShift Container Platform 4.18: 4.8, 4.9
• Red Hat Single Sign-On: 7.0, 7.5.0

How to fix

Upgrade to a fixed version: Keycloak 18.0.0. Check the vendor advisory for mitigations.

References

• https://access.redhat.com/security/cve/CVE-2021-3827
• https://bugzilla.redhat.com/show_bug.cgi?id=2007512
• https://github.com/keycloak/keycloak/commit/44000caaf5051d7f218d1ad79573bd3d175cad0d
• https://github.com/keycloak/keycloak/security/advisories/GHSA-4pc7-vqv5-5r3v
• https://access.redhat.com/security/cve/CVE-2021-3827
• https://bugzilla.redhat.com/show_bug.cgi?id=2007512
• https://github.com/keycloak/keycloak/commit/44000caaf5051d7f218d1ad79573bd3d175cad0d
• https://github.com/keycloak/keycloak/security/advisories/GHSA-4pc7-vqv5-5r3v

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