# CVE-2021-3916: Path Traversal in bookstackapp/bookstack

> An attacker can exploit a path traversal vulnerability in BookStack to read arbitrary files from the server.

- **Severity:** Medium 6.5 (`CVSS:3.0/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:** No
- **Published:** 5 Nov 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-g66g-3vwf-hfgf

## What is CVE-2021-3916?

CVE-2021-3916 is a medium-severity path traversal vulnerability in bookstackapp/bookstack, published on 5 Nov 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

bookstack is vulnerable to Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

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

## Which versions are affected by CVE-2021-3916?

It affects 1 product.


Products: Bookstackapp Bookstack.

## How do I fix CVE-2021-3916?

No fix has been published for CVE-2021-3916 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-3916 being exploited?

There is no known exploitation of CVE-2021-3916 in the wild and no public exploit code.

## Other vulnerabilities in bookstackapp/bookstack

- [CVE-2020-5256](https://insights.sbomify.com/CVE-2020-5256/): Remote Code Execution Through Image Uploads in BookStack (high 7.9)
- [CVE-2020-26210](https://insights.sbomify.com/CVE-2020-26210/): Cross-Site Scripting in BookStack (high 7.7)
- [CVE-2020-26211](https://insights.sbomify.com/CVE-2020-26211/): Cross-Site Scripting in BookStack (high 7.7)
- [CVE-2022-0877](https://insights.sbomify.com/CVE-2022-0877/): Cross-site Scripting (XSS) - Stored in bookstackapp/bookstack (high 7.6)
- [CVE-2021-3915](https://insights.sbomify.com/CVE-2021-3915/): Unrestricted Upload of File with Dangerous Type in bookstackapp/bookstack (high 7.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-3916 and fix it if it is affected.

What it is: CVE-2021-3916 is a medium-severity path traversal vulnerability in bookstackapp/bookstack, published on 5 Nov 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-2021-3916 in the wild and no public exploit code.

Affected product: bookstackapp/bookstack. 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-2021-3916/ (Markdown: https://insights.sbomify.com/CVE-2021-3916/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3916
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3916
- OSV: https://osv.dev/vulnerability/CVE-2021-3916

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-3916/
Summaries are generated and may contain mistakes; the official description above is the record.