# CVE-2021-20133: Path traversal in Quagga Services on D-Link DIR-2640 Routers

> Authenticated attackers can read arbitrary files or cause denial of service on D-Link DIR-2640 routers via path traversal in Quagga services.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 30 Dec 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-3398-v46q-wcp6

## What is CVE-2021-20133?

CVE-2021-20133 is a medium-severity path traversal vulnerability in Quagga Services on D-Link DIR-2640 Routers, published on 30 Dec 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Quagga Services on D-Link DIR-2640 less than or equal to version 1.11B02 are affected by an absolute path traversal vulnerability that allows a remote, authenticated attacker to set the "message of the day" banner to any file on the system, allowing them to read all or some of the contents of those files. Such sensitive information as hashed credentials, hardcoded plaintext passwords for other services, configuration files, and private keys can be disclosed in this fashion. Improper handling of filenames that identify virtual resources, such as "/dev/urandom" allows an attacker to effect a denial of service attack against the command line interfaces of the Quagga services (zebra and ripd).

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2021-20133?

It affects 1 product.


Products: Dlink Dir-2640-Us Firmware.

## How do I fix CVE-2021-20133?

No fix has been published for CVE-2021-20133 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-20133 being exploited?

There is no known exploitation of CVE-2021-20133 in the wild and no public exploit code.

## Other vulnerabilities in Quagga Services on D-Link DIR-2640 Routers

- [CVE-2021-20132](https://insights.sbomify.com/CVE-2021-20132/): Hardcoded credentials in Quagga Services on D-Link DIR-2640 Routers (high 8.8)
- [CVE-2021-20134](https://insights.sbomify.com/CVE-2021-20134/): Path traversal in Quagga Services on D-Link DIR-2640 Routers (high 8.4)
- [CVE-2021-34203](https://insights.sbomify.com/CVE-2021-34203/): Hardcoded credentials in n/a (high 8.1)
- [CVE-2021-34202](https://insights.sbomify.com/CVE-2021-34202/): Memory corruption in n/a (high 7.8)
- [CVE-2021-34201](https://insights.sbomify.com/CVE-2021-34201/): Memory corruption in n/a (high 7.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20133 and fix it if it is affected.

What it is: CVE-2021-20133 is a medium-severity path traversal vulnerability in Quagga Services on D-Link DIR-2640 Routers, published on 30 Dec 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-2021-20133 in the wild and no public exploit code.

Affected product: Quagga Services on D-Link DIR-2640 Routers. 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-2021-20133/ (Markdown: https://insights.sbomify.com/CVE-2021-20133/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20133
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20133
- OSV: https://osv.dev/vulnerability/CVE-2021-20133

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-20133/
Summaries are generated and may contain mistakes; the official description above is the record.