# CVE-2020-26210: Cross-Site Scripting in BookStack

> An attacker with page edit permissions can inject malicious JavaScript that executes when other users view the page, potentially leading to session hijacking or data theft.

- **Severity:** High 7.7 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 3 Nov 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-7p2j-4h6p-cq3h, GHSA-vmfp-7cw6-345x

## What is CVE-2020-26210?

CVE-2020-26210 is a high-severity cross-site scripting vulnerability in BookStackApp BookStack, published on 3 Nov 2020. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

In BookStack before version 0.30.4, a user with permissions to edit a page could add an attached link which would execute untrusted JavaScript code when clicked by a viewer of the page. Dangerous content may remain in the database after this update. If you think this could have been exploited the linked advisory provides a SQL query to test. As a workaround, page edit permissions could be limited to only those that are trusted until you can upgrade although this will not address existing exploitation of this vulnerability. The issue is fixed in version 0.30.4.

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

## Which versions are affected by CVE-2020-26210?

It affects 1 product.


Products: Bookstackapp Bookstack.

## How do I fix CVE-2020-26210?

No fix has been published for CVE-2020-26210 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-26210 being exploited?

There is no known exploitation of CVE-2020-26210 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-2020-26211](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)
- [CVE-2023-6199](https://insights.sbomify.com/CVE-2023-6199/): Book Stack v23.10.2 - LFR via Blind SSRF (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-26210 and fix it if it is affected.

What it is: CVE-2020-26210 is a high-severity cross-site scripting vulnerability in BookStackApp BookStack, published on 3 Nov 2020. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2020-26210 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-2020-26210/ (Markdown: https://insights.sbomify.com/CVE-2020-26210/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-26210
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-26210
- OSV: https://osv.dev/vulnerability/CVE-2020-26210

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-26210/
Summaries are generated and may contain mistakes; the official description above is the record.