# CVE-2016-9920: Command injection in n/a

> Authenticated attackers can execute arbitrary code via crafted email requests when sendmail is enabled without SMTP configuration.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 Dec 2016
- **Updated:** 6 Aug 2024
- **Also known as:** CVE-2017-1000204, DEBIAN-CVE-2016-9920, DLA-737-1, GHSA-f59r-7mfp-ww98, MGASA-2016-0430, UBUNTU-CVE-2016-9920

## What is CVE-2016-9920?

CVE-2016-9920 is a high-severity command injection vulnerability in Roundcube Webmail, published on 8 Dec 2016. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

steps/mail/sendmail.inc in Roundcube before 1.1.7 and 1.2.x before 1.2.3, when no SMTP server is configured and the sendmail program is enabled, does not properly restrict the use of custom envelope-from addresses on the sendmail command line, which allows remote authenticated users to execute arbitrary code via a modified HTTP request that sends a crafted e-mail message.

Weakness: CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2016-9920?

It affects 1 product.


Products: Roundcube Webmail.

## How do I fix CVE-2016-9920?

Upgrade to a fixed version.

## Is CVE-2016-9920 being exploited?

There is no known exploitation of CVE-2016-9920 in the wild and no public exploit code.

Public exploit code:

- Roundcube 1.0.0 <= 1.2.2 Remote Code Execution exploit and vulnerable container (github_poc): https://github.com/t0kx/exploit-CVE-2016-9920

## Other vulnerabilities in Roundcube Webmail

- [CVE-2024-42009](https://insights.sbomify.com/CVE-2024-42009/): RoundCube Webmail Cross-Site Scripting (critical 9.3, exploited in the wild)
- [CVE-2025-68461](https://insights.sbomify.com/CVE-2025-68461/): RoundCube Webmail Cross-site Scripting (high 7.2, exploited in the wild)
- [CVE-2008-5619](https://insights.sbomify.com/CVE-2008-5619/): PHPMailer susceptible to arbitrary code execution (critical 10.0)
- [CVE-2024-37385](https://insights.sbomify.com/CVE-2024-37385/): Command injection in n/a (critical 9.8)
- [CVE-2024-42008](https://insights.sbomify.com/CVE-2024-42008/): Cross-site scripting in n/a (critical 9.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-9920 and fix it if it is affected.

What it is: CVE-2016-9920 is a high-severity command injection vulnerability in Roundcube Webmail, published on 8 Dec 2016. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2016-9920 in the wild and no public exploit code.

Affected product: Roundcube Webmail. 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-2016-9920/ (Markdown: https://insights.sbomify.com/CVE-2016-9920/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-9920
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-9920
- OSV: https://osv.dev/vulnerability/CVE-2016-9920

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-9920/
Summaries are generated and may contain mistakes; the official description above is the record.