# CVE-2018-3963: Command injection in CUJO

> Attackers can execute arbitrary system commands on CUJO Smart Firewalls by sending malicious DHCP requests with unsanitized hostnames.

- **Severity:** Critical 9.0 (`CVSS:3.0/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 Mar 2019
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-665f-qp36-gp6g

## What is CVE-2018-3963?

CVE-2018-3963 is a critical command injection vulnerability in CUJO, published on 21 Mar 2019. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An exploitable command injection vulnerability exists in the DHCP daemon configuration of the CUJO Smart Firewall. When adding a new static DHCP address, its corresponding hostname is inserted into the dhcpd.conf file without prior sanitization, allowing for arbitrary execution of system commands. To trigger this vulnerability, an attacker can send a DHCP request message and set up the corresponding static DHCP entry.

Weakness: CWE-77 (Improper Neutralization of Special Elements used in a Command)

## Which versions are affected by CVE-2018-3963?

It affects 1 product.


Products: Getcujo Smart Firewall.

## How do I fix CVE-2018-3963?

No fix has been published for CVE-2018-3963 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-3963 being exploited?

There is no known exploitation of CVE-2018-3963 in the wild and no public exploit code.

## Other vulnerabilities in CUJO

- [CVE-2018-4031](https://insights.sbomify.com/CVE-2018-4031/): Code 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-2018-3963 and fix it if it is affected.

What it is: CVE-2018-3963 is a critical command injection vulnerability in CUJO, published on 21 Mar 2019. 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-2018-3963 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-2018-3963/ (Markdown: https://insights.sbomify.com/CVE-2018-3963/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-3963
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-3963
- OSV: https://osv.dev/vulnerability/CVE-2018-3963

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-3963/
Summaries are generated and may contain mistakes; the official description above is the record.