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CVE-2021-4133

29
FAUCET Score

CVE-2021-4133 is a high-severity vulnerability affecting Keycloak versions 12.0.0 through 15.1.0, allowing an authenticated attacker to create new default user accounts via the administrative REST API, even when new user registration is disabled. With a CVSS score of 8.8, this flaw presents a low-complexity attack vector that can lead to high impact on confidentiality, integrity, and availability. While the vulnerability is not listed on the KEV catalog and has no known public exploits or significant community discussion, its potential for unauthorized account creation poses a significant risk. Organizations using affected Keycloak versions should prioritize patching to mitigate this threat.

Impacted Technologies

VendorProductVersion(s)CPE
>= 12.0.0, < 15.1.1CPE matchmatch criteria
cpe:2.3:a:redhat:keycloak:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.35%
Probability of exploitation in next 30 days
EPSS Percentile
68.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0135 is in the 66th percentile among its peer group of 17,823 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (11)

mavenpatch availablevia ghsa
Product: org.keycloak:keycloak-servicesFixed in: 15.1.1
redhatpatch availablevia redhat_api
Product: Red Hat Single Sign-On 7.5 for RHEL 7Fixed in: rh-sso7-keycloak-0:15.0.2-3.redhat_00002.1.el7sso
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Single Sign-On 7.5 for RHEL 7Fixed in: rh-sso7-keycloak-0:15.0.4-1.redhat_00001.1.el7sso
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Single Sign-On 7.5 for RHEL 8Fixed in: rh-sso7-keycloak-0:15.0.2-3.redhat_00002.1.el8sso
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Single Sign-On 7.5 for RHEL 8Fixed in: rh-sso7-keycloak-0:15.0.4-1.redhat_00001.1.el8sso
View patch
redhatpatch availablevia redhat_api
Product: RHEL-8 based Middleware ContainersFixed in: rh-sso-7/sso75-openshift-rhel8:7.5-11
View patch
redhatpatch availablevia redhat_api
Product: RHEL-8 based Middleware ContainersFixed in: rh-sso-7/sso7-rhel8-operator-bundle:7.5.0-11
View patch
redhatpatch availablevia redhat_api
Product: RHEL-8 based Middleware ContainersFixed in: rh-sso-7/sso7-rhel8-operator-bundle:7.5.0-12
View patch
redhatpatch availablevia redhat_api
Product: RHEL-8 based Middleware ContainersFixed in: rh-sso-7/sso75-openshift-rhel8:7.5-15
View patch
redhatpatch availablevia redhat_api
Product: RHSSO 7.5.1Fixed in: keycloak-services
View patch
redhatpatch availablevia redhat_api
Product: RHSSO 7.5 async for CVE-2021-4133Fixed in: keycloak-services
View patch

Vendor Advisories (2)

mavenGHSA-83x4-9cwr-5487high

Improper Authorization in Keycloak

Jan 6, 2022
redhatCVE-2021-4133Important

Keycloak: Incorrect authorization allows unpriviledged users to create other users

Dec 16, 2021

References

bugzilla.redhat.com / show_bug.cgi
Issue TrackingThird Party Advisory
github.com / keycloak/keycloak/issues/9247
Third Party Advisory
github.com / keycloak/keycloak/security/advisories/GHSA-83x4-9cwr-5487
Third Party Advisory
oracle.com / security-alerts/cpuapr2022.html
Not Applicable