# CVE-2021-23021: Information disclosure in Nginx Controller

> Local attackers can read sensitive agent configuration files due to world-readable permissions, potentially exposing credentials or secrets.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 Jun 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-2ffq-2568-c74h

## What is CVE-2021-23021?

CVE-2021-23021 is a medium-severity vulnerability in Nginx Controller, published on 1 Jun 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The Nginx Controller 3.x before 3.7.0 agent configuration file /etc/controller-agent/agent.conf is world readable with current permission bits set to 644.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource)

## Which versions are affected by CVE-2021-23021?

It affects 1 product.


Products: F5 Nginx Controller.

## How do I fix CVE-2021-23021?

No fix has been published for CVE-2021-23021 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-23021 being exploited?

There is no known exploitation of CVE-2021-23021 in the wild and no public exploit code.

## Other vulnerabilities in Nginx Controller

- [CVE-2020-27730](https://insights.sbomify.com/CVE-2020-27730/): Path traversal in NGINX Controller (critical 9.8)
- [CVE-2020-5901](https://insights.sbomify.com/CVE-2020-5901/): Cross-site scripting in NGINX Controller (critical 9.6)
- [CVE-2020-5900](https://insights.sbomify.com/CVE-2020-5900/): Cross-site request forgery in NGINX Controller (high 8.8)
- [CVE-2020-5863](https://insights.sbomify.com/CVE-2020-5863/): Missing authorization in NGINX Controller (high 8.6)
- [CVE-2020-5894](https://insights.sbomify.com/CVE-2020-5894/): Security feature bypass in NGINX Controller (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-23021 and fix it if it is affected.

What it is: CVE-2021-23021 is a medium-severity vulnerability in Nginx Controller, published on 1 Jun 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-23021 in the wild and no public exploit code.

Affected product: Nginx Controller. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2021-23021/ (Markdown: https://insights.sbomify.com/CVE-2021-23021/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-23021
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-23021
- OSV: https://osv.dev/vulnerability/CVE-2021-23021

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-23021/
Summaries are generated and may contain mistakes; the official description above is the record.