# CVE-2021-44521: Remote code execution for scripted UDFs

> Attackers with UDF creation permissions can execute arbitrary code on Apache Cassandra hosts when unsafe scripted UDF settings are enabled.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Feb 2022
- **Updated:** 4 Aug 2024
- **Also known as:** BIT-cassandra-2021-44521, ECHO-2550-1834-d752, GHSA-8ffc-79xg-29w8, MINI-4jjc-74vc-3j6j, MINI-mxmp-hw8g-mq2f

## What is CVE-2021-44521?

CVE-2021-44521 is a critical code injection vulnerability in Apache Cassandra, published on 11 Feb 2022. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

When running Apache Cassandra with the following configuration: enable_user_defined_functions: true enable_scripted_user_defined_functions: true enable_user_defined_functions_threads: false it is possible for an attacker to execute arbitrary code on the host. The attacker would need to have enough permissions to create user defined functions in the cluster to be able to exploit this. Note that this configuration is documented as unsafe, and will continue to be considered unsafe after this CVE.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource), CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2021-44521?

7 open source packages ship an affected version, including org.apache.cassandra:cassandra-all and cassandra. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `org.apache.cassandra:cassandra-all` | Maven | All versions | 3.0.26 |
| `org.apache.cassandra:cassandra-all` | Maven | All versions | 3.0.26 |
| `org.apache.cassandra:cassandra-all` | Maven | From 3.11.0 | 3.11.12 |
| `org.apache.cassandra:cassandra-all` | Maven | From 3.11.0 | 3.11.12 |
| `org.apache.cassandra:cassandra-all` | Maven | From 4.0.0 | 4.0.2 |
| `org.apache.cassandra:cassandra-all` | Maven | From 4.0.0 | 4.0.2 |
| `cassandra` | Bitnami | From 3.0.0 | 3.0.26, 3.11.12, 4.0.2 |

Products: Apache Cassandra.

## How do I fix CVE-2021-44521?

Upgrade org.apache.cassandra:cassandra-all to a fixed version for your release line: 3.0.26, 3.11.12 or 4.0.2.

## Is CVE-2021-44521 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-44521 exists.

Public exploit code:

- Automated PoC of CVE-2021-44521 (github_poc): https://github.com/WoodenKlaas/CVE-2021-44521
- full PoC of CVE-2021-44521  (github_poc): https://github.com/Yeyvo/poc-CVE-2021-44521
- Apache Cassandra Load UDF RCE (nuclei)

## Other vulnerabilities in Apache Cassandra

- [CVE-2016-3427](https://insights.sbomify.com/CVE-2016-3427/): Oracle Java SE and JRockit Unspecified (critical 9.8, exploited in the wild)
- [CVE-2018-8016](https://insights.sbomify.com/CVE-2018-8016/): Missing Authentication for Critical Function in Apache Cassandra (critical 9.8)
- [CVE-2026-27314](https://insights.sbomify.com/CVE-2026-27314/): Apache Cassandra: Privilege escalation via ADD IDENTITY authorization bypass (high 8.8)
- [CVE-2025-26467](https://insights.sbomify.com/CVE-2025-26467/): Apache Cassandra: User with MODIFY permission on ALL KEYSPACES can escalate privileges to superuser via unsafe actions (4.0.16 only) (high 8.8)
- [CVE-2025-23015](https://insights.sbomify.com/CVE-2025-23015/): Apache Cassandra: User with MODIFY permission on ALL KEYSPACES can escalate privileges to superuser via unsafe actions (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-44521 and fix it if it is affected.

What it is: CVE-2021-44521 is a critical code injection vulnerability in Apache Cassandra, published on 11 Feb 2022. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-44521 exists.

Affected packages and fixed versions:
- org.apache.cassandra:cassandra-all (Maven): affected all versions; fixed in 3.0.26
- org.apache.cassandra:cassandra-all (Maven): affected all versions; fixed in 3.0.26
- org.apache.cassandra:cassandra-all (Maven): affected from 3.11.0; fixed in 3.11.12
- org.apache.cassandra:cassandra-all (Maven): affected from 3.11.0; fixed in 3.11.12
- org.apache.cassandra:cassandra-all (Maven): affected from 4.0.0; fixed in 4.0.2
- org.apache.cassandra:cassandra-all (Maven): affected from 4.0.0; fixed in 4.0.2
- cassandra (Bitnami): affected from 3.0.0; fixed in 3.0.26, 3.11.12, 4.0.2

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-2021-44521/ (Markdown: https://insights.sbomify.com/CVE-2021-44521/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-44521
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-44521
- OSV: https://osv.dev/vulnerability/CVE-2021-44521

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-44521/
Summaries are generated and may contain mistakes; the official description above is the record.