# CVE-2024-45800: Multiple mXSS found in snappymail HTML parser

> Attackers can inject JavaScript via malformed HTML in emails, potentially leading to code execution or data leakage through proxy requests.

- **Severity:** Medium 5.0 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 16 Sep 2024
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-2rq7-79vp-ffxm

## What is CVE-2024-45800?

CVE-2024-45800 is a medium-severity cross-site scripting vulnerability in the-djmaze snappymail, published on 16 Sep 2024. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Snappymail is an open source web-based email client. SnappyMail uses the `cleanHtml()` function to cleanup HTML and CSS in emails. Research discovered that the function has a few bugs which cause an mXSS exploit. Because the function allowed too many (invalid) HTML elements, it was possible (with incorrect markup) to trick the browser to "fix" the broken markup into valid markup. As a result a motivated attacker may be able to inject javascript. However, due to the default Content Security Policy the impact of the exploit is minimal. It could be possible to create an attack which leaks some data when loading images through the proxy.
This way it might be possible to use the proxy to attack the local system, like with `http://localhost:5000/leak`. Another attack could be to load a JavaScript attachment of the email. This is very tricky as the email must link to every possible UID as each email has a unique UID which has a value between 1 and 18446744073709551615 **v2.38.0** and up now remove unsupported HTML elements which mitigates the issue. Users are advised to upgrade. Older versions can install an extension named "Security mXSS" as a mitigation. This will be available at the administration area at `/?admin#/packages`. **NOTE:** this extension can not "fix" malicious code in encrypted messages or (html) attachments as it can't manipulate the JavaScript code for this. It only protects normal message HTML.

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

## Which versions are affected by CVE-2024-45800?


## How do I fix CVE-2024-45800?

No fix has been published for CVE-2024-45800 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-45800 being exploited?

There is no known exploitation of CVE-2024-45800 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-45800 and fix it if it is affected.

What it is: CVE-2024-45800 is a medium-severity cross-site scripting vulnerability in the-djmaze snappymail, published on 16 Sep 2024. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2024-45800 in the wild and no public exploit code.

Affected product: the-djmaze snappymail. 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-2024-45800/ (Markdown: https://insights.sbomify.com/CVE-2024-45800/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-45800
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-45800
- OSV: https://osv.dev/vulnerability/CVE-2024-45800

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From sbomify Insights: https://insights.sbomify.com/CVE-2024-45800/
Summaries are generated and may contain mistakes; the official description above is the record.