# CVE-2020-7616: Improperly Controlled Modification of Dynamically-Determined Object Attributes in express-mock-middleware

> Attackers can achieve code execution via prototype pollution in express-mock-middleware if they can place malicious code in a new directory.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Apr 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-v39h-qm32-8gwq

## What is CVE-2020-7616?

CVE-2020-7616 is a medium-severity code injection vulnerability in express-mock-middleware, published on 7 Apr 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

express-mock-middleware through 0.0.6 is vulnerable to Prototype Pollution. Exported functions by the package can be tricked into adding or modifying properties of the `Object.prototype`. Exploitation of this vulnerability requires creation of a new directory where an attack code can be placed which will then be exported by `express-mock-middleware`. As such, this is considered to be a low risk.

Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2020-7616?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `express-mock-middleware` | npm | All versions to 0.0.6 | None |
| `express-mock-middleware` | npm | All versions to 0.0.6 | None |

Products: Express-Mock-Middleware Project Express-Mock-Middleware.

## How do I fix CVE-2020-7616?

No fix has been published for CVE-2020-7616 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-7616 being exploited?

There is no known exploitation of CVE-2020-7616 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-7616 and fix it if it is affected.

What it is: CVE-2020-7616 is a medium-severity code injection vulnerability in express-mock-middleware, published on 7 Apr 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-7616 in the wild and no public exploit code.

Affected packages and fixed versions:
- express-mock-middleware (npm): affected all versions up to 0.0.6; no fix listed
- express-mock-middleware (npm): affected all versions up to 0.0.6; no fix listed

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-2020-7616/ (Markdown: https://insights.sbomify.com/CVE-2020-7616/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-7616
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-7616
- OSV: https://osv.dev/vulnerability/CVE-2020-7616

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-7616/
Summaries are generated and may contain mistakes; the official description above is the record.