# CVE-2020-28477: Prototype Pollution

> Prototype pollution in the immer library allows attackers to modify object prototypes, potentially leading to code execution or denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:U/RC:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Jan 2021
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-9qmh-276g-x5pj, ROOT-APP-NPM-CVE-2020-28477

## What is CVE-2020-28477?

CVE-2020-28477 is a high-severity vulnerability in immer, published on 19 Jan 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

This affects all versions of package immer.

## Which versions are affected by CVE-2020-28477?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `immer` | npm | From 7.0.0 | 8.0.1 |
| `immer` | npm | From 7.0.0 | 8.0.1 |

Products: Immer Project Immer.

## How do I fix CVE-2020-28477?

Upgrade immer to 8.0.1 or later.

## Is CVE-2020-28477 being exploited?

There is no known exploitation of CVE-2020-28477 in the wild and no public exploit code.

## Other vulnerabilities in immer

- [CVE-2021-3757](https://insights.sbomify.com/CVE-2021-3757/): Prototype Pollution in immerjs/immer (high 7.5)
- [CVE-2021-23436](https://insights.sbomify.com/CVE-2021-23436/): Prototype Pollution (medium 5.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-28477 and fix it if it is affected.

What it is: CVE-2020-28477 is a high-severity vulnerability in immer, published on 19 Jan 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-2020-28477 in the wild and no public exploit code.

Affected packages and fixed versions:
- immer (npm): affected from 7.0.0; fixed in 8.0.1
- immer (npm): affected from 7.0.0; fixed in 8.0.1

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-2020-28477/ (Markdown: https://insights.sbomify.com/CVE-2020-28477/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-28477
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-28477
- OSV: https://osv.dev/vulnerability/CVE-2020-28477

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-28477/
Summaries are generated and may contain mistakes; the official description above is the record.