# GHSA-7cg8-pq9v-x98q: Sandbox Breakout in realms-shim

> Attackers can break out of the realms-shim sandbox by providing a malicious rewriter function, leading to arbitrary code execution.

- **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:** 21 Oct 2019

## What is GHSA-7cg8-pq9v-x98q?

GHSA-7cg8-pq9v-x98q is a code injection vulnerability in realms-shim, published on 21 Oct 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Versions of `realms-shim` prior to 1.2.1 are vulnerable to a Sandbox Breakout. The Realms evaluation function has an option to apply Babel-like transformations to the source code before it reaches the evaluator. One portion of this transform pipeline exposed a primal-Realm object to the rewriting function. Confined code which used the evaluator itself could provide a malicious rewriter function that captured this object, and use it to breach the sandbox.

## Recommendation

Upgrade to version 1.2.1 or later.

## Which versions are affected by GHSA-7cg8-pq9v-x98q?

2 open source packages ship an affected version, including realms-shim.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `realms-shim` | npm | All versions | 1.2.1 |
| `realms-shim` | npm | All versions | 1.2.1 |

## How do I fix GHSA-7cg8-pq9v-x98q?

Upgrade realms-shim to 1.2.1 or later.

## Is GHSA-7cg8-pq9v-x98q being exploited?

There is no known exploitation of GHSA-7cg8-pq9v-x98q in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-7cg8-pq9v-x98q and fix it if it is affected.

What it is: GHSA-7cg8-pq9v-x98q is a code injection vulnerability in realms-shim, published on 21 Oct 2019. 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-7cg8-pq9v-x98q in the wild and no public exploit code.

Affected packages and fixed versions:
- realms-shim (npm): affected all versions; fixed in 1.2.1
- realms-shim (npm): affected all versions; fixed in 1.2.1

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/GHSA-7cg8-pq9v-x98q/ (Markdown: https://insights.sbomify.com/GHSA-7cg8-pq9v-x98q/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-7cg8-pq9v-x98q

---
From sbomify Insights: https://insights.sbomify.com/GHSA-7cg8-pq9v-x98q/
Summaries are generated and may contain mistakes; the official description above is the record.