# CVE-2021-4133: Improper Authorization in Keycloak

> An attacker with any user account can create new default users via the admin API even when registration is disabled, bypassing access controls.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Jan 2022
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-83x4-9cwr-5487, RHSA-2021:5218, RHSA-2021:5219

## What is CVE-2021-4133?

CVE-2021-4133 is a high-severity missing authorization vulnerability in Redhat Keycloak, published on 25 Jan 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 in versions from 12.0.0 and before 15.1.1 which allows an attacker with any existing user account to create new default user accounts via the administrative REST API even when new user registration is disabled.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2021-4133?

2 open source packages ship an affected version, including org.keycloak:keycloak-services. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `org.keycloak:keycloak-services` | Maven | All versions | 15.1.1 |
| `org.keycloak:keycloak-services` | Maven | All versions | 15.1.1 |
| `rh-sso7-keycloak` | Red Hat:red_hat_single_sign_on:7.5::el7 | All versions | 0:15.0.2-3.redhat_00002.1.el7sso |
| `rh-sso7-keycloak-server` | Red Hat:red_hat_single_sign_on:7.5::el7 | All versions | 0:15.0.2-3.redhat_00002.1.el7sso |
| `rh-sso7-keycloak` | Red Hat:red_hat_single_sign_on:7.5::el8 | All versions | 0:15.0.2-3.redhat_00002.1.el8sso |
| `rh-sso7-keycloak-server` | Red Hat:red_hat_single_sign_on:7.5::el8 | All versions | 0:15.0.2-3.redhat_00002.1.el8sso |

Products: Redhat Keycloak.

## How do I fix CVE-2021-4133?

Upgrade org.keycloak:keycloak-services to 15.1.1 or later.

## Is CVE-2021-4133 being exploited?

There is no known exploitation of CVE-2021-4133 in the wild and no public exploit code.

## Other vulnerabilities in Redhat Keycloak

- [CVE-2022-4361](https://insights.sbomify.com/CVE-2022-4361/): Keycloak vulnerable to cross-site scripting when validating URI-schemes on SAML and OIDC (critical 10.0)
- [CVE-2022-1245](https://insights.sbomify.com/CVE-2022-1245/): Keycloak vulnerable to privilege escalation on Token Exchange feature (critical 9.8)
- [CVE-2021-20195](https://insights.sbomify.com/CVE-2021-20195/): keycloak Self Stored Cross-site Scripting vulnerability (critical 9.6)
- [CVE-2019-14910](https://insights.sbomify.com/CVE-2019-14910/): Keycloak Authentication Error (critical 9.3)
- [CVE-2019-14909](https://insights.sbomify.com/CVE-2019-14909/): Keycloak Authentication Error (critical 9.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-4133 and fix it if it is affected.

What it is: CVE-2021-4133 is a high-severity missing authorization vulnerability in Redhat Keycloak, published on 25 Jan 2022. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-4133 in the wild and no public exploit code.

Affected packages and fixed versions:
- org.keycloak:keycloak-services (Maven): affected all versions; fixed in 15.1.1
- org.keycloak:keycloak-services (Maven): affected all versions; fixed in 15.1.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-4133/ (Markdown: https://insights.sbomify.com/CVE-2021-4133/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-4133
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-4133
- OSV: https://osv.dev/vulnerability/CVE-2021-4133

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-4133/
Summaries are generated and may contain mistakes; the official description above is the record.