# CVE-2021-21422: XSS Vulnerability in mongo-express

> An attacker can inject JavaScript via large document fields or media cells in mongo-express, potentially stealing data or executing commands when an admin views the content.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N`)
- **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:** Yes
- **Published:** 21 Jun 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-7p8h-86p5-wv3p

## What is CVE-2021-21422?

CVE-2021-21422 is a high-severity cross-site scripting vulnerability in mongo-express, published on 21 Jun 2021. 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

mongo-express is a web-based MongoDB admin interface, written with Node.js and express. 1: As mentioned in this issue: https://github.com/mongo-express/mongo-express/issues/577, when the content of a cell grows larger than supported size, clicking on a row will show full document unescaped, however this needs admin interaction on cell. 2: Data cells identified as media will be rendered as media, without being sanitized. Example of different renders: image, audio, video, etc. As an example of type 1 attack, an unauthorized user who only can send a large amount of data in a field of a document may use a payload with embedded javascript. This could send an export of a collection to the attacker without even an admin knowing. Other types of attacks such as dropping a database\collection are possible.

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

## Which versions are affected by CVE-2021-21422?

2 open source packages ship an affected version, including mongo-express. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mongo-express` | npm | All versions | 1.0.0-alpha.4 |
| `mongo-express` | npm | All versions | 1.0.0-alpha.4 |

Products: Mongo-Express Project Mongo-Express.

## How do I fix CVE-2021-21422?

Upgrade mongo-express to 1.0.0-alpha.4 or later.

## Is CVE-2021-21422 being exploited?

There is no known exploitation of CVE-2021-21422 in the wild and no public exploit code.

## Other vulnerabilities in mongo-express

- [CVE-2019-10758](https://insights.sbomify.com/CVE-2019-10758/): MongoDB mongo-express Remote Code Execution (critical 9.9, exploited in the wild)
- [CVE-2020-24391](https://insights.sbomify.com/CVE-2020-24391/): Remote code execution in mongo-express (critical 9.8)
- [CVE-2023-52555](https://insights.sbomify.com/CVE-2023-52555/): mongo-express Cross-site Request Forgery vulnerability (medium 6.1)
- [CVE-2021-23372](https://insights.sbomify.com/CVE-2021-23372/): Denial of Service (DoS) (medium 4.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-21422 and fix it if it is affected.

What it is: CVE-2021-21422 is a high-severity cross-site scripting vulnerability in mongo-express, published on 21 Jun 2021. 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-2021-21422 in the wild and no public exploit code.

Affected packages and fixed versions:
- mongo-express (npm): affected all versions; fixed in 1.0.0-alpha.4
- mongo-express (npm): affected all versions; fixed in 1.0.0-alpha.4

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-2021-21422/ (Markdown: https://insights.sbomify.com/CVE-2021-21422/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-21422
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-21422
- OSV: https://osv.dev/vulnerability/CVE-2021-21422

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-21422/
Summaries are generated and may contain mistakes; the official description above is the record.