# CVE-2020-5420: Gorouter is vulnerable to DoS attack via invalid HTTP responses

> A malicious developer can crash Cloud Foundry Gorouters by pushing an app with crafted HTTP responses, causing cluster-wide denial of service.

- **Severity:** High 7.7 (`CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/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:** No
- **Published:** 3 Sep 2020
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-jf63-p3cp-7qf7

## What is CVE-2020-5420?

CVE-2020-5420 is a high-severity denial of service vulnerability in Cloud Foundry CF Deployment, published on 3 Sep 2020. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Cloud Foundry Routing (Gorouter) versions prior to 0.206.0 allow a malicious developer with "cf push" access to cause denial-of-service to the CF cluster by pushing an app that returns specially crafted HTTP responses that crash the Gorouters.

Weakness: CWE-754 (Improper Check for Unusual or Exceptional Conditions)

## Which versions are affected by CVE-2020-5420?

It affects 2 products.


Products: Cloudfoundry Cf-Deployment, Cloudfoundry Gorouter.

## How do I fix CVE-2020-5420?

No fix has been published for CVE-2020-5420 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-5420 being exploited?

There is no known exploitation of CVE-2020-5420 in the wild and no public exploit code.

## Other vulnerabilities in Cloud Foundry CF Deployment

- [CVE-2022-31733](https://insights.sbomify.com/CVE-2022-31733/): Auth bypass in Cloud Foundry Diego and CF Deployment (critical 9.1)
- [CVE-2020-5402](https://insights.sbomify.com/CVE-2020-5402/): UAA fails to check the state parameter when authenticating with external IDPs (high 8.8)
- [CVE-2019-11293](https://insights.sbomify.com/CVE-2019-11293/): UAA logs all query parameters with debug logging level (high 8.8)
- [CVE-2019-11290](https://insights.sbomify.com/CVE-2019-11290/): Cloud Foundry UAA logs query parameters in tomcat access file (high 8.8)
- [CVE-2019-11283](https://insights.sbomify.com/CVE-2019-11283/): Password leak in smbdriver logs (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-5420 and fix it if it is affected.

What it is: CVE-2020-5420 is a high-severity denial of service vulnerability in Cloud Foundry CF Deployment, published on 3 Sep 2020. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-5420 in the wild and no public exploit code.

Affected product: Cloud Foundry CF Deployment. 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-2020-5420/ (Markdown: https://insights.sbomify.com/CVE-2020-5420/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-5420
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-5420
- OSV: https://osv.dev/vulnerability/CVE-2020-5420

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-5420/
Summaries are generated and may contain mistakes; the official description above is the record.