# CVE-2021-32662: TechDocs mkdocs.yml path traversal

> Attackers with source code access can read sensitive files via path traversal in mkdocs.yml configuration, exposing data through the TechDocs API.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/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:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Jun 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-pgf8-28gg-vpr6

## What is CVE-2021-32662?

CVE-2021-32662 is a medium-severity path traversal vulnerability in Linuxfoundation Backstage, published on 3 Jun 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Backstage is an open platform for building developer portals, and techdocs-common contains common functionalities for Backstage's TechDocs. In `@backstage/techdocs-common` versions prior to 0.6.3, a malicious actor could read sensitive files from the environment where TechDocs documentation is built and published by setting a particular path for `docs_dir` in `mkdocs.yml`. These files would then be available over the TechDocs backend API. This vulnerability is mitigated by the fact that an attacker would need access to modify the `mkdocs.yml` in the documentation source code, and would also need access to the TechDocs backend API. The vulnerability is patched in the `0.6.3` release of `@backstage/techdocs-common`.

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

## Which versions are affected by CVE-2021-32662?

2 open source packages ship an affected version, including @backstage/techdocs-common. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@backstage/techdocs-common` | npm | All versions | 0.6.3 |
| `@backstage/techdocs-common` | npm | All versions | 0.6.3 |

Products: Linuxfoundation Backstage.

## How do I fix CVE-2021-32662?

Upgrade @backstage/techdocs-common to 0.6.3 or later.

## Is CVE-2021-32662 being exploited?

There is no known exploitation of CVE-2021-32662 in the wild and no public exploit code.

## Other vulnerabilities in Linuxfoundation Backstage

- [CVE-2026-106501](https://insights.sbomify.com/CVE-2026-106501/): Backstage: Sensitive information exposure in Scaffolder (critical 9.6)
- [CVE-2026-106558](https://insights.sbomify.com/CVE-2026-106558/): Backstage: Improper validation of TechDocs MkDocs configuration (high 8.8)
- [CVE-2026-88064](https://insights.sbomify.com/CVE-2026-88064/): Backstage: Improper input validation in TechDocs MkDocs configuration (high 8.8)
- [CVE-2026-106459](https://insights.sbomify.com/CVE-2026-106459/): Backstage: Improper input validation in Sentry scaffolder actions (high 8.5)
- [CVE-2026-106486](https://insights.sbomify.com/CVE-2026-106486/): Backstage: Improper filesystem validation in Bitbucket pull-request scaffolder actions (high 8.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-32662 and fix it if it is affected.

What it is: CVE-2021-32662 is a medium-severity path traversal vulnerability in Linuxfoundation Backstage, published on 3 Jun 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-32662 in the wild and no public exploit code.

Affected packages and fixed versions:
- @backstage/techdocs-common (npm): affected all versions; fixed in 0.6.3
- @backstage/techdocs-common (npm): affected all versions; fixed in 0.6.3

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-2021-32662/ (Markdown: https://insights.sbomify.com/CVE-2021-32662/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32662
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32662
- OSV: https://osv.dev/vulnerability/CVE-2021-32662

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32662/
Summaries are generated and may contain mistakes; the official description above is the record.