# CVE-2021-4279: Starcounter-Jack JSON-Patch prototype pollution

> Remote attackers can exploit prototype pollution in the JSON-Patch library to potentially execute code or escalate privileges.

- **Severity:** Medium 6.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Dec 2022
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-8gh8-hqwg-xf34

## What is CVE-2021-4279?

CVE-2021-4279 is a medium-severity vulnerability in Starcounter-Jack JSON-Patch, published on 25 Dec 2022. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability has been found in Starcounter-Jack JSON-Patch up to 3.1.0 and classified as problematic. This vulnerability affects unknown code. The manipulation leads to improperly controlled modification of object prototype attributes ('prototype pollution'). The attack can be initiated remotely. The exploit has been disclosed to the public and may be used. Upgrading to version 3.1.1 is able to address this issue. The name of the patch is 7ad6af41eabb2d799f698740a91284d762c955c9. It is recommended to upgrade the affected component. VDB-216778 is the identifier assigned to this vulnerability.

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

## Which versions are affected by CVE-2021-4279?

2 open source packages ship an affected version, including fast-json-patch. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `fast-json-patch` | npm | All versions | 3.1.1 |
| `fast-json-patch` | npm | All versions | 3.1.1 |

Products: Starcounter-Jack Json-Patch.

## How do I fix CVE-2021-4279?

Upgrade fast-json-patch to 3.1.1 or later.

## Is CVE-2021-4279 being exploited?

There is no known exploitation of CVE-2021-4279 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-4279 and fix it if it is affected.

What it is: CVE-2021-4279 is a medium-severity vulnerability in Starcounter-Jack JSON-Patch, published on 25 Dec 2022. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-4279 in the wild and no public exploit code.

Affected packages and fixed versions:
- fast-json-patch (npm): affected all versions; fixed in 3.1.1
- fast-json-patch (npm): affected all versions; fixed in 3.1.1

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-2021-4279/ (Markdown: https://insights.sbomify.com/CVE-2021-4279/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-4279
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-4279
- OSV: https://osv.dev/vulnerability/CVE-2021-4279

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-4279/
Summaries are generated and may contain mistakes; the official description above is the record.