# CVE-2018-20434: LibreNMS arbitrary OS commands execution

> Remote attackers can execute arbitrary OS commands in LibreNMS by injecting malicious input during device creation and triggering a specific capture request.

- **Severity:** Critical 9.8 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/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:** 24 Apr 2019
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-62q7-qj6g-gvr7

## What is CVE-2018-20434?

CVE-2018-20434 is a critical command injection vulnerability in Librenms Librenms, published on 24 Apr 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

LibreNMS 1.46 allows remote attackers to execute arbitrary OS commands by using the $_POST['community'] parameter to html/pages/addhost.inc.php during creation of a new device, and then making a /ajax_output.php?id=capture&format=text&type=snmpwalk&hostname=localhost request that triggers html/includes/output/capture.inc.php command mishandling.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2018-20434?

2 open source packages ship an affected version, including librenms/librenms. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `librenms/librenms` | Packagist | All versions | None |
| `librenms/librenms` | Packagist | All versions | None |

Products: Librenms Librenms.

## How do I fix CVE-2018-20434?

No fix has been published for CVE-2018-20434 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-20434 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2018-20434 exists.

Public exploit code:

- The official exploit code for LibreNMS v1.46 Remote Code Execution CVE-2018-20434 (github_poc): https://github.com/mhaskar/CVE-2018-20434
- LibreNMS addhost Command Injection (metasploit)
- LibreNMS - addhost Command Injection (Metasploit) (exploitdb)
- LibreNMS 1.46 - 'addhost' Remote Code Execution (exploitdb)

## Other vulnerabilities in Librenms Librenms

- [CVE-2023-4982](https://insights.sbomify.com/CVE-2023-4982/): Cross-site Scripting (XSS) - Stored in librenms/librenms (critical 9.8)
- [CVE-2022-29712](https://insights.sbomify.com/CVE-2022-29712/): Command injection in librenms (critical 9.8)
- [CVE-2021-44278](https://insights.sbomify.com/CVE-2021-44278/): Path traversal in librenms/librenms (critical 9.8)
- [CVE-2019-10665](https://insights.sbomify.com/CVE-2019-10665/): LibreNMS Information Disclosure (critical 9.8)
- [CVE-2026-26988](https://insights.sbomify.com/CVE-2026-26988/): LibreNMS: SQL Injection in ajax_table.php spreads through a covert data stream (critical 9.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-20434 and fix it if it is affected.

What it is: CVE-2018-20434 is a critical command injection vulnerability in Librenms Librenms, published on 24 Apr 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2018-20434 exists.

Affected packages and fixed versions:
- librenms/librenms (Packagist): affected all versions; no fix listed
- librenms/librenms (Packagist): affected all versions; no fix listed

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-2018-20434/ (Markdown: https://insights.sbomify.com/CVE-2018-20434/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-20434
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-20434
- OSV: https://osv.dev/vulnerability/CVE-2018-20434

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-20434/
Summaries are generated and may contain mistakes; the official description above is the record.