# CVE-2020-36178: Command injection in n/a

> Attackers can execute arbitrary OS commands on TP-Link TL-WR840N routers via IP address fields in the web interface due to unsafe system calls.

- **Severity:** Critical 9.8 (`CVSS:3.1/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:** 6 Jan 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-qqg6-4j54-68gr

## What is CVE-2020-36178?

CVE-2020-36178 is a critical command injection vulnerability in n/a, published on 6 Jan 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

oal_ipt_addBridgeIsolationRules on TP-Link TL-WR840N 6_EU_0.9.1_4.16 devices allows OS command injection because a raw string entered from the web interface (an IP address field) is used directly for a call to the system library function (for iptables). NOTE: oal_ipt_addBridgeIsolationRules is not the only function that calls util_execSystem.

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

## Which versions are affected by CVE-2020-36178?

It affects 1 product.


Products: Tp-Link Tl-Wr840n Firmware.

## How do I fix CVE-2020-36178?

No fix has been published for CVE-2020-36178 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-36178 being exploited?

There is no known exploitation of CVE-2020-36178 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2022-25060](https://insights.sbomify.com/CVE-2022-25060/): Command injection in n/a (critical 9.8)
- [CVE-2022-25061](https://insights.sbomify.com/CVE-2022-25061/): Command injection in n/a (critical 9.8)
- [CVE-2022-25064](https://insights.sbomify.com/CVE-2022-25064/): Command injection in n/a (critical 9.8)
- [CVE-2021-41653](https://insights.sbomify.com/CVE-2021-41653/): Command injection in n/a (critical 9.8)
- [CVE-2018-11714](https://insights.sbomify.com/CVE-2018-11714/): Auth bypass in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-36178 and fix it if it is affected.

What it is: CVE-2020-36178 is a critical command injection vulnerability in n/a, published on 6 Jan 2021. 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-2020-36178 in the wild and no public exploit code.

Affected product: n/a. 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-2020-36178/ (Markdown: https://insights.sbomify.com/CVE-2020-36178/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-36178
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-36178
- OSV: https://osv.dev/vulnerability/CVE-2020-36178

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-36178/
Summaries are generated and may contain mistakes; the official description above is the record.