# CVE-2020-25109: Denial of service in n/a

> Attackers can cause denial of service or potentially execute code by sending malformed DNS packets to Ethernut Nut/OS devices.

- **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:** 11 Dec 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-w9cm-mhh5-jvr7

## What is CVE-2020-25109?

CVE-2020-25109 is a critical denial of service vulnerability in n/a, published on 11 Dec 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in the DNS implementation in Ethernut in Nut/OS 5.1. The number of DNS queries/responses (set in a DNS header) is not checked against the data present. This may lead to successful Denial-of-Service, and possibly Remote Code Execution.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2020-25109?

It affects 1 product.


Products: Ethernut Nut\/Os.

## How do I fix CVE-2020-25109?

No fix has been published for CVE-2020-25109 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-25109 being exploited?

There is no known exploitation of CVE-2020-25109 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2020-25107](https://insights.sbomify.com/CVE-2020-25107/): Memory corruption in n/a (critical 9.8)
- [CVE-2020-25108](https://insights.sbomify.com/CVE-2020-25108/): Memory corruption in n/a (critical 9.8)
- [CVE-2020-25110](https://insights.sbomify.com/CVE-2020-25110/): Memory corruption in n/a (critical 9.8)
- [CVE-2020-27213](https://insights.sbomify.com/CVE-2020-27213/): Weak cryptography in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-25109 and fix it if it is affected.

What it is: CVE-2020-25109 is a critical denial of service vulnerability in n/a, published on 11 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-2020-25109 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-2020-25109/ (Markdown: https://insights.sbomify.com/CVE-2020-25109/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-25109
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-25109
- OSV: https://osv.dev/vulnerability/CVE-2020-25109

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-25109/
Summaries are generated and may contain mistakes; the official description above is the record.