# CVE-2021-20323: Cross-site Scripting in Keycloak

> Attackers can execute arbitrary scripts in victim browsers via reflected XSS in Keycloak, potentially compromising user sessions.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 25 Mar 2022
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-xpgc-j48j-jwv9

## What is CVE-2021-20323?

CVE-2021-20323 is a medium-severity cross-site scripting vulnerability in Redhat Keycloak, published on 25 Mar 2022. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A POST based reflected Cross Site Scripting vulnerability on has been identified in Keycloak.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2021-20323?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `org.keycloak:keycloak-core` | Maven | From 15.0.0 | 17.0.0 |
| `org.keycloak:keycloak-core` | Maven | From 15.0.0 | 17.0.0 |

Products: Redhat Keycloak.

## How do I fix CVE-2021-20323?

Upgrade org.keycloak:keycloak-core to 17.0.0 or later.

## Is CVE-2021-20323 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-20323 exists.

Public exploit code:

- https://github.com/ndmalc/CVE-2021-20323 (github_poc): https://github.com/ndmalc/CVE-2021-20323
- A POST based reflected Cross Site Scripting vulnerability on has been identified in Keycloak. (github_poc): https://github.com/Cappricio-Securities/CVE-2021-20323
- Exploitation Scanner Cross Site Scripting vulnerability in Keycloak. (github_poc): https://github.com/cscpwn0sec/CVE-2021-20323
- Keycloak 10.0.0 - 18.0.0 - Cross-Site Scripting (nuclei): http/cves/2021/CVE-2021-20323.yaml

## 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-2021-20323 and fix it if it is affected.

What it is: CVE-2021-20323 is a medium-severity cross-site scripting vulnerability in Redhat Keycloak, published on 25 Mar 2022. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-20323 exists.

Affected packages and fixed versions:
- org.keycloak:keycloak-core (Maven): affected from 15.0.0; fixed in 17.0.0
- org.keycloak:keycloak-core (Maven): affected from 15.0.0; fixed in 17.0.0

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-2021-20323/ (Markdown: https://insights.sbomify.com/CVE-2021-20323/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20323
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20323
- OSV: https://osv.dev/vulnerability/CVE-2021-20323

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-20323/
Summaries are generated and may contain mistakes; the official description above is the record.