# CVE-2023-43656: Sandbox escape for instances that have enabled transformation functions in matrix-hookshot

> Attackers can escape the vm2 sandbox to execute arbitrary code if JavaScript transformation functions are enabled for untrusted users.

- **Severity:** Medium 5.6 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Sep 2023
- **Updated:** 20 Sep 2024
- **Also known as:** GHSA-fr97-pv6w-4cj6

## What is CVE-2023-43656?

CVE-2023-43656 is a medium-severity code injection vulnerability in matrix-org matrix-hookshot, published on 27 Sep 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

matrix-hookshot is a Matrix bot for connecting to external services like GitHub, GitLab, JIRA, and more. Instances that have enabled transformation functions (those that have `generic.allowJsTransformationFunctions` in their config), may be vulnerable to an attack where it is possible to break out of the `vm2` sandbox and as a result Hookshot will be vulnerable to this. This problem is only likely to affect users who have allowed untrusted users to apply their own transformation functions. If you have only enabled a limited set of trusted users, this threat is reduced (though not eliminated). Version 4.5.0 and above of hookshot include a new sandbox library which should better protect users. Users are advised to upgrade. Users unable to upgrade should disable `generic.allowJsTransformationFunctions` in the config.

Weakness: CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component)

## Which versions are affected by CVE-2023-43656?

It affects 1 product.


Products: Matrix Hookshot.

## How do I fix CVE-2023-43656?

No fix has been published for CVE-2023-43656 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-43656 being exploited?

There is no known exploitation of CVE-2023-43656 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-43656 and fix it if it is affected.

What it is: CVE-2023-43656 is a medium-severity code injection vulnerability in matrix-org matrix-hookshot, published on 27 Sep 2023. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-43656 in the wild and no public exploit code.

Affected product: matrix-org matrix-hookshot. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2023-43656/ (Markdown: https://insights.sbomify.com/CVE-2023-43656/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-43656
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-43656
- OSV: https://osv.dev/vulnerability/CVE-2023-43656

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-43656/
Summaries are generated and may contain mistakes; the official description above is the record.