# CVE-2021-4119: Improper Access Control in bookstackapp/bookstack

> An attacker can bypass access controls in BookStack to read or modify unauthorized data.

- **Severity:** Medium 5.3 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Dec 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-9c5c-5j4h-8q2c

## What is CVE-2021-4119?

CVE-2021-4119 is a medium-severity missing authorization vulnerability in bookstackapp/bookstack, published on 15 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

bookstack is vulnerable to Improper Access Control

Weakness: CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2021-4119?

2 open source packages ship an affected version, including ssddanbrown/bookstack. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ssddanbrown/bookstack` | Packagist | All versions | 21.11.3 |
| `ssddanbrown/bookstack` | Packagist | All versions | 21.11.3 |

Products: Bookstackapp Bookstack.

## How do I fix CVE-2021-4119?

Upgrade ssddanbrown/bookstack to 21.11.3 or later.

## Is CVE-2021-4119 being exploited?

There is no known exploitation of CVE-2021-4119 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-2021-4119 and fix it if it is affected.

What it is: CVE-2021-4119 is a medium-severity missing authorization vulnerability in bookstackapp/bookstack, published on 15 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-4119 in the wild and no public exploit code.

Affected packages and fixed versions:
- ssddanbrown/bookstack (Packagist): affected all versions; fixed in 21.11.3
- ssddanbrown/bookstack (Packagist): affected all versions; fixed in 21.11.3

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-2021-4119/ (Markdown: https://insights.sbomify.com/CVE-2021-4119/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-4119
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-4119
- OSV: https://osv.dev/vulnerability/CVE-2021-4119

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-4119/
Summaries are generated and may contain mistakes; the official description above is the record.