# CVE-2020-7770: Prototype Pollution

> Prototype pollution in json8 allows attackers to modify object prototypes, potentially leading to code execution or privilege escalation.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/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:** 12 Nov 2020
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-7h43-gx24-p529, SNYK-JS-JSON8-1017116

## What is CVE-2020-7770?

CVE-2020-7770 is a medium-severity vulnerability in json8, published on 12 Nov 2020. 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

This affects the package json8 before 1.0.3. The function adds in the target object the property specified in the path, however it does not properly check the key being set, leading to a prototype pollution.

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

## Which versions are affected by CVE-2020-7770?

2 open source packages ship an affected version, including json8. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `json8` | npm | All versions | 1.0.3 |
| `json8` | npm | All versions | 1.0.3 |

Products: Json8 Project Json8.

## How do I fix CVE-2020-7770?

Upgrade json8 to 1.0.3 or later.

## Is CVE-2020-7770 being exploited?

There is no known exploitation of CVE-2020-7770 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-7770 and fix it if it is affected.

What it is: CVE-2020-7770 is a medium-severity vulnerability in json8, published on 12 Nov 2020. 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-2020-7770 in the wild and no public exploit code.

Affected packages and fixed versions:
- json8 (npm): affected all versions; fixed in 1.0.3
- json8 (npm): affected all versions; fixed in 1.0.3

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-2020-7770/ (Markdown: https://insights.sbomify.com/CVE-2020-7770/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-7770
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-7770
- OSV: https://osv.dev/vulnerability/CVE-2020-7770

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-7770/
Summaries are generated and may contain mistakes; the official description above is the record.