# CVE-2020-28499: Prototype Pollution

> The merge library is vulnerable to prototype pollution, potentially allowing attackers to modify object prototypes and execute arbitrary code or escalate privileges.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Feb 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-7wpw-2hjm-89gp, ROOT-APP-NPM-CVE-2020-28499

## What is CVE-2020-28499?

CVE-2020-28499 is a high-severity vulnerability in merge, published on 18 Feb 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

All versions of package merge are vulnerable to Prototype Pollution via _recursiveMerge .

## Which versions are affected by CVE-2020-28499?

2 open source packages ship an affected version, including merge. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `merge` | npm | All versions | 2.1.1 |
| `merge` | npm | All versions | 2.1.1 |

Products: Merge Project Merge.

## How do I fix CVE-2020-28499?

Upgrade merge to 2.1.1 or later.

## Is CVE-2020-28499 being exploited?

There is no known exploitation of CVE-2020-28499 in the wild and no public exploit code.

## Other vulnerabilities in merge

- [CVE-2018-16469](https://insights.sbomify.com/CVE-2018-16469/): Prototype Pollution in merge (high 7.5)
- [CVE-2021-3645](https://insights.sbomify.com/CVE-2021-3645/): Prototype Pollution in viking04/merge (medium 6.8)
- [CVE-2021-23397](https://insights.sbomify.com/CVE-2021-23397/): Prototype Pollution (medium 5.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-28499 and fix it if it is affected.

What it is: CVE-2020-28499 is a high-severity vulnerability in merge, published on 18 Feb 2021. 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-2020-28499 in the wild and no public exploit code.

Affected packages and fixed versions:
- merge (npm): affected all versions; fixed in 2.1.1
- merge (npm): affected all versions; fixed in 2.1.1

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-2020-28499/ (Markdown: https://insights.sbomify.com/CVE-2020-28499/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-28499
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-28499
- OSV: https://osv.dev/vulnerability/CVE-2020-28499

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-28499/
Summaries are generated and may contain mistakes; the official description above is the record.