Skip to content
Fencer Vulns
medium 6.8

CVE-2021-3827 json

ECP SAML binding bypasses authentication flows

published 2022-04-27 4 y ago modified 2026-07-08 4 mo ago also GHSA-4pc7-vqv5-5r3v , EUVD-2022-1622

cvss
6.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 66%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven org.keycloak:keycloak-saml-core 18.0.0
  • redhat keycloak 18.0.0
  • rh-sso7-keycloak red hat single sign on 7.5 15.0.4-1.redhat_00001.1.el7sso
  • rh-sso7-keycloak-server red hat single sign on 7.5 15.0.4-1.redhat_00001.1.el7sso
  • rh-sso7-keycloak red hat single sign on 7.5 15.0.4-1.redhat_00001.1.el8sso
  • rh-sso7-keycloak-server red hat single sign on 7.5 15.0.4-1.redhat_00001.1.el8sso

red hat advisories RHSA-2022:0151RHSA-2022:0152

  • keycloak Arch Linux 16.0.0-1

arch linux advisories AVG-1332

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-3827 updated cvss 6.8

keycloak-server-spi-private: ECP SAML binding bypasses authentication flows

  • Red Hat A-MQ Online keycloak-server-spi-private
    affected: no fix planned “Out of support scope”
  • Red Hat Middleware Containers for OpenShift rh-sso-7/sso75-openshift-rhel8 7.5-15
    fixed: vendor fix RHSA-2022:0164
  • Red Hat Single Sign-On 7.5 for RHEL 7 Server rh-sso7-keycloak 15.0.4-1.redhat_00001.1.el7sso, rh-sso7-keycloak-server 15.0.4-1.redhat_00001.1.el7sso
    fixed: vendor fix RHSA-2022:0151
  • Red Hat Single Sign-On 7.5 for RHEL 8 rh-sso7-keycloak 15.0.4-1.redhat_00001.1.el8sso, rh-sso7-keycloak-server 15.0.4-1.redhat_00001.1.el8sso
    fixed: vendor fix RHSA-2022:0152
  • Red Hat RHSSO 7.5.1
    fixed: vendor fix RHSA-2022:0155

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.11% chance of exploitation in the next 30 days, higher than 66% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 6.8 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
GitHub 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
maven org.keycloak:keycloak-saml-core
<18.0.0
18.0.0

Affected products

  • n/a keycloak

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.