# CVE-2024-40626: Stored Cross-site Scripting (XSS) vulnerability in Outline editor

> Authenticated users can inject malicious scripts via document attachments in self-hosted Outline instances, potentially executing code in other users' browsers.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/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:** 16 Jul 2024
- **Updated:** 2 Aug 2024
- **Also known as:** GHSA-888c-mvg8-v6wh

## What is CVE-2024-40626?

CVE-2024-40626 is a high-severity cross-site scripting vulnerability in outline, published on 16 Jul 2024. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Outline is an open source, collaborative document editor. A type confusion issue was found in ProseMirror’s rendering process that leads to a Stored Cross-Site Scripting (XSS) vulnerability in Outline. An authenticated user can create a document containing a malicious JavaScript payload. When other users view this document, the malicious Javascript can execute in the origin of Outline. Outline includes CSP rules to prevent third-party code execution, however in the case of self-hosting and having your file storage on the same domain as Outline a malicious payload can be uploaded as a file attachment and bypass those CSP restrictions. This issue has been addressed in release version 0.77.3. Users are advised to upgrade. There are no known workarounds for this vulnerability.

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

## Which versions are affected by CVE-2024-40626?

It affects 1 product.


Products: Getoutline Outline.

## How do I fix CVE-2024-40626?

No fix has been published for CVE-2024-40626 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-40626 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2024-40626 exists.

## Other vulnerabilities in outline

- [CVE-2026-33640](https://insights.sbomify.com/CVE-2026-33640/): Outline has a rate limit bypass that allows brute force of email login OTP (critical 9.1)
- [CVE-2024-37829](https://insights.sbomify.com/CVE-2024-37829/): Auth bypass in n/a (high 8.8)
- [CVE-2023-54331](https://insights.sbomify.com/CVE-2023-54331/): Outline 1.6.0 - Unquoted Service Path (high 8.5)
- [CVE-2023-3532](https://insights.sbomify.com/CVE-2023-3532/): Cross-site Scripting (XSS) - Stored in outline/outline (high 8.5)
- [CVE-2026-24901](https://insights.sbomify.com/CVE-2026-24901/): Outline's IDOR allows unauthorized viewing and seizing of private deleted drafts (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-40626 and fix it if it is affected.

What it is: CVE-2024-40626 is a high-severity cross-site scripting vulnerability in outline, published on 16 Jul 2024. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2024-40626 exists.

Affected product: outline. 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-2024-40626/ (Markdown: https://insights.sbomify.com/CVE-2024-40626/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-40626
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-40626
- OSV: https://osv.dev/vulnerability/CVE-2024-40626

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-40626/
Summaries are generated and may contain mistakes; the official description above is the record.