# CVE-2018-4031: Code injection in CUJO

> An attacker can execute arbitrary Lua code in the kernel by sending a malicious HTTP request to the CUJO Smart Firewall's safe browsing function.

- **Severity:** Critical 9.0 (`CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 31 Oct 2019
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-m3xq-c6mf-v376

## What is CVE-2018-4031?

CVE-2018-4031 is a critical code injection vulnerability in CUJO, published on 31 Oct 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An exploitable vulnerability exists in the safe browsing function of the CUJO Smart Firewall, version 7003. The flaw lies in the way the safe browsing function parses HTTP requests. The server hostname is extracted from captured HTTP/HTTPS requests and inserted as part of a Lua statement without prior sanitization, which results in arbitrary Lua script execution in the kernel. An attacker could send an HTTP request to exploit this vulnerability.

Weakness: CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2018-4031?

It affects 1 product.


Products: Getcujo Smart Firewall.

## How do I fix CVE-2018-4031?

No fix has been published for CVE-2018-4031 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-4031 being exploited?

There is no known exploitation of CVE-2018-4031 in the wild and no public exploit code.

## Other vulnerabilities in CUJO

- [CVE-2018-3963](https://insights.sbomify.com/CVE-2018-3963/): Command injection in CUJO (critical 9.0)
- [CVE-2018-3985](https://insights.sbomify.com/CVE-2018-3985/): Use after free in CUJO (high 8.3)
- [CVE-2018-4003](https://insights.sbomify.com/CVE-2018-4003/): Memory corruption in CUJO (high 8.3)
- [CVE-2018-3969](https://insights.sbomify.com/CVE-2018-3969/): Command injection in CUJO (high 8.2)
- [CVE-2018-4011](https://insights.sbomify.com/CVE-2018-4011/): Integer overflow in CUJO (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-4031 and fix it if it is affected.

What it is: CVE-2018-4031 is a critical code injection vulnerability in CUJO, published on 31 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 CVE-2018-4031 in the wild and no public exploit code.

Affected product: CUJO. 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-2018-4031/ (Markdown: https://insights.sbomify.com/CVE-2018-4031/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-4031
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-4031
- OSV: https://osv.dev/vulnerability/CVE-2018-4031

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From sbomify Insights: https://insights.sbomify.com/CVE-2018-4031/
Summaries are generated and may contain mistakes; the official description above is the record.