# CVE-2020-18723: Cross-site scripting in n/a

> Stored XSS in MDaemon webmail allows attackers to execute code on email recipients' browsers via malicious file attachments.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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 Feb 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-7c3h-wh3g-298c

## What is CVE-2020-18723?

CVE-2020-18723 is a medium-severity cross-site scripting vulnerability in n/a, published on 3 Feb 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Stored cross-site scripting (XSS) in file attachment field in MDaemon webmail 19.5.5 allows an attacker to execute code on the email recipient side while forwarding an email to perform potentially malicious activities.

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

## Which versions are affected by CVE-2020-18723?

It affects 1 product.


Products: Altn Mdaemon Webmail.

## How do I fix CVE-2020-18723?

No fix has been published for CVE-2020-18723 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-18723 being exploited?

There is no known exploitation of CVE-2020-18723 in the wild and no public exploit code.

Public exploit code:

- Alt-N MDaemon webmail 20.0.0 - 'file name' Stored Cross Site Scripting (XSS) (exploitdb)

## Other vulnerabilities in n/a

- [CVE-2018-17792](https://insights.sbomify.com/CVE-2018-17792/): Cross-site request forgery in n/a (high 8.8)
- [CVE-2020-18724](https://insights.sbomify.com/CVE-2020-18724/): Cross-site scripting in n/a (medium 5.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-18723 and fix it if it is affected.

What it is: CVE-2020-18723 is a medium-severity cross-site scripting vulnerability in n/a, published on 3 Feb 2021. 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-2020-18723 in the wild and no public exploit code.

Affected product: n/a. 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-2020-18723/ (Markdown: https://insights.sbomify.com/CVE-2020-18723/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-18723
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-18723
- OSV: https://osv.dev/vulnerability/CVE-2020-18723

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-18723/
Summaries are generated and may contain mistakes; the official description above is the record.