# CVE-2020-11055: Cross-site Scripting in BookStack

> An attacker with comment permissions can inject malicious JavaScript into BookStack comments, executing code on other users' browsers.

- **Severity:** Medium 6.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L`)
- **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:** 7 May 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-5vf7-q87h-pg6w

## What is CVE-2020-11055?

CVE-2020-11055 is a medium-severity cross-site scripting vulnerability in BookStackApp BookStack, published on 7 May 2020. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

In BookStack greater than or equal to 0.18.0 and less than 0.29.2, there is an XSS vulnerability in comment creation. A user with permission to create comments could POST HTML directly to the system to be saved in a comment, which would then be executed/displayed to others users viewing the comment. Through this vulnerability custom JavaScript code could be injected and therefore ran on other user machines. This most impacts scenarios where not-trusted users are given permission to create comments. This has been fixed in 0.29.2.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2020-11055?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ssddanbrown/bookstack` | Packagist | From 0.18.0 | 0.29.2 |
| `ssddanbrown/bookstack` | Packagist | From 0.18.0 | 0.29.2 |

Products: Bookstackapp Bookstack.

## How do I fix CVE-2020-11055?

Upgrade ssddanbrown/bookstack to 0.29.2 or later.

## Is CVE-2020-11055 being exploited?

There is no known exploitation of CVE-2020-11055 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-2020-11055 and fix it if it is affected.

What it is: CVE-2020-11055 is a medium-severity cross-site scripting vulnerability in BookStackApp BookStack, published on 7 May 2020. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-11055 in the wild and no public exploit code.

Affected packages and fixed versions:
- ssddanbrown/bookstack (Packagist): affected from 0.18.0; fixed in 0.29.2
- ssddanbrown/bookstack (Packagist): affected from 0.18.0; fixed in 0.29.2

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-2020-11055/ (Markdown: https://insights.sbomify.com/CVE-2020-11055/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-11055
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-11055
- OSV: https://osv.dev/vulnerability/CVE-2020-11055

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-11055/
Summaries are generated and may contain mistakes; the official description above is the record.