# CVE-2020-5423: Cloud Controller is vulnerable to denial of service via YAML parsing

> Unauthenticated attackers can cause denial of service in Cloud Foundry CAPI by sending crafted YAML files that exhaust CPU and RAM resources.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 2 Dec 2020
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-jj4c-53qh-fp5v

## What is CVE-2020-5423?

CVE-2020-5423 is a high-severity denial of service vulnerability in Cloud Foundry CAPI, published on 2 Dec 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

CAPI (Cloud Controller) versions prior to 1.101.0 are vulnerable to a denial-of-service attack in which an unauthenticated malicious attacker can send specially-crafted YAML files to certain endpoints, causing the YAML parser to consume excessive CPU and RAM.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2020-5423?

It affects 2 products.


Products: Cloudfoundry Capi-Release, Cloudfoundry Cf-Deployment.

## How do I fix CVE-2020-5423?

No fix has been published for CVE-2020-5423 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-5423 being exploited?

There is no known exploitation of CVE-2020-5423 in the wild and no public exploit code.

## Other vulnerabilities in Cloud Foundry CAPI

- [CVE-2018-1195](https://insights.sbomify.com/CVE-2018-1195/): Auth bypass in Cloud Controller (high 8.8)
- [CVE-2020-5417](https://insights.sbomify.com/CVE-2020-5417/): Cloud Controller may allow developers to claim sensitive routes (high 8.5)
- [CVE-2023-20881](https://insights.sbomify.com/CVE-2023-20881/): Missing authorization in Cloud Controller API (high 8.1)
- [CVE-2018-1266](https://insights.sbomify.com/CVE-2018-1266/): Path traversal in n/a (high 8.1)
- [CVE-2020-5400](https://insights.sbomify.com/CVE-2020-5400/): Cloud Controller logs environment variables from app manifests (high 8.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-5423 and fix it if it is affected.

What it is: CVE-2020-5423 is a high-severity denial of service vulnerability in Cloud Foundry CAPI, published on 2 Dec 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-2020-5423 in the wild and no public exploit code.

Affected product: Cloud Foundry CAPI. 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-2020-5423/ (Markdown: https://insights.sbomify.com/CVE-2020-5423/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-5423
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-5423
- OSV: https://osv.dev/vulnerability/CVE-2020-5423

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-5423/
Summaries are generated and may contain mistakes; the official description above is the record.