# GHSA-779f-wgxg-qr8f: Prototype Pollution in lodash.mergewith

> Attackers can pollute the Object prototype via mergeWith, potentially leading to code execution or privilege escalation in applications using this library.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Sep 2020

## What is GHSA-779f-wgxg-qr8f?

GHSA-779f-wgxg-qr8f is a vulnerability in lodash.mergewith, published on 3 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Versions of `lodash.mergewith` before 4.6.2 are vulnerable to prototype pollution. The function `mergeWith` may allow a malicious user to modify the prototype of `Object` via `{constructor: {prototype: {...}}}` causing the addition or modification of an existing property that will exist on all objects.

## Recommendation

Update to version 4.6.2 or later.

## Which versions are affected by GHSA-779f-wgxg-qr8f?

2 open source packages ship an affected version, including lodash.mergewith.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `lodash.mergewith` | npm | All versions | 4.6.2 |
| `lodash.mergewith` | npm | All versions | 4.6.2 |

## How do I fix GHSA-779f-wgxg-qr8f?

Upgrade lodash.mergewith to 4.6.2 or later.

## Is GHSA-779f-wgxg-qr8f being exploited?

There is no known exploitation of GHSA-779f-wgxg-qr8f in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-779f-wgxg-qr8f and fix it if it is affected.

What it is: GHSA-779f-wgxg-qr8f is a vulnerability in lodash.mergewith, published on 3 Sep 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 GHSA-779f-wgxg-qr8f in the wild and no public exploit code.

Affected packages and fixed versions:
- lodash.mergewith (npm): affected all versions; fixed in 4.6.2
- lodash.mergewith (npm): affected all versions; fixed in 4.6.2

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/GHSA-779f-wgxg-qr8f/ (Markdown: https://insights.sbomify.com/GHSA-779f-wgxg-qr8f/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-779f-wgxg-qr8f

---
From sbomify Insights: https://insights.sbomify.com/GHSA-779f-wgxg-qr8f/
Summaries are generated and may contain mistakes; the official description above is the record.