# CVE-2020-3161: Cisco IP Phones Web Server Remote Code Execution and Denial-of-Service

> Unauthenticated remote attackers can execute code with root privileges or cause a denial of service on Cisco IP Phones via crafted HTTP requests.

- **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:** Yes, since 3 Nov 2021 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Apr 2020
- **Updated:** 21 Oct 2025
- **Also known as:** GHSA-74vv-6p4c-8fhj

## What is CVE-2020-3161?

CVE-2020-3161 is a critical command injection vulnerability in Cisco IP phone, published on 15 Apr 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the web server for Cisco IP Phones could allow an unauthenticated, remote attacker to execute code with root privileges or cause a reload of an affected IP phone, resulting in a denial of service (DoS) condition. The vulnerability is due to a lack of proper input validation of HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the web server of a targeted device. A successful exploit could allow the attacker to remotely execute code with root privileges or cause a reload of an affected IP phone, resulting in a DoS condition.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2020-3161?

It affects 13 products.


Products: Cisco 8831 Firmware, Cisco Ip Phone 7811 Firmware, Cisco Ip Phone 7821 Firmware, Cisco Ip Phone 7841 Firmware, Cisco Ip Phone 7861 Firmware, Cisco Ip Phone 8811 Firmware, Cisco Ip Phone 8821-Ex Firmware, Cisco Ip Phone 8821 Firmware, Cisco Ip Phone 8841 Firmware, Cisco Ip Phone 8845 Firmware, Cisco Ip Phone 8851 Firmware, Cisco Ip Phone 8861 Firmware, Cisco Ip Phone 8865 Firmware.

## How do I fix CVE-2020-3161?

No fix has been published for CVE-2020-3161 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 3 May 2022.

## Is CVE-2020-3161 being exploited?

Yes. Attackers have exploited CVE-2020-3161 in the wild since at least 3 Nov 2021.

Public exploit code:

- Cisco IP Phone 11.7 - Denial of service (PoC) (exploitdb)
- Cisco IP Phone 11.7 - Denial of Service (PoC) (github_poc): https://github.com/abood05972/CVE-2020-3161

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-3161 and fix it if it is affected.

What it is: CVE-2020-3161 is a critical command injection vulnerability in Cisco IP phone, published on 15 Apr 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2020-3161 in the wild since at least 3 Nov 2021.

Affected product: Cisco IP phone. 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-2020-3161/ (Markdown: https://insights.sbomify.com/CVE-2020-3161/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-3161
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-3161
- OSV: https://osv.dev/vulnerability/CVE-2020-3161

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-3161/
Summaries are generated and may contain mistakes; the official description above is the record.