# CVE-2020-13485: Knock Knock plugin IP Whitelist bypass via an X-Forwarded-For HTTP header

> Attackers can bypass IP whitelist restrictions in the Knock Knock plugin for Craft CMS by spoofing the X-Forwarded-For header.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 May 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-wxvr-qqm7-6h65

## What is CVE-2020-13485?

CVE-2020-13485 is a critical vulnerability in n/a, published on 25 May 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Knock Knock plugin before 1.2.8 for Craft CMS allows IP Whitelist bypass via an X-Forwarded-For HTTP header.

Weakness: CWE-697 (Incorrect Comparison)

## Which versions are affected by CVE-2020-13485?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `verbb/knock-knock` | Packagist | All versions | 1.2.8 |
| `verbb/knock-knock` | Packagist | All versions | 1.2.8 |

Products: Verbb Knock Knock.

## How do I fix CVE-2020-13485?

Upgrade verbb/knock-knock to 1.2.8 or later.

## Is CVE-2020-13485 being exploited?

There is no known exploitation of CVE-2020-13485 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2020-13486](https://insights.sbomify.com/CVE-2020-13486/): Knock Knock plugin Open redirection vulnerability (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-13485 and fix it if it is affected.

What it is: CVE-2020-13485 is a critical vulnerability in n/a, published on 25 May 2020. 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-2020-13485 in the wild and no public exploit code.

Affected packages and fixed versions:
- verbb/knock-knock (Packagist): affected all versions; fixed in 1.2.8
- verbb/knock-knock (Packagist): affected all versions; fixed in 1.2.8

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-2020-13485/ (Markdown: https://insights.sbomify.com/CVE-2020-13485/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-13485
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-13485
- OSV: https://osv.dev/vulnerability/CVE-2020-13485

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-13485/
Summaries are generated and may contain mistakes; the official description above is the record.