# CVE-2020-17440: Null dereference in n/a

> Attackers can cause a denial of service in uIP by sending malformed DNS packets that trigger an invalid pointer dereference during name parsing.

- **Severity:** High 7.5 (`CVSS:3.1/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:** 11 Dec 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-3jjq-5484-vh7r

## What is CVE-2020-17440?

CVE-2020-17440 is a high-severity 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 uIP 1.0, as used in Contiki 3.0 and other products. The code that parses incoming DNS packets does not validate that domain names present in the DNS responses have '\0' termination. This results in errors when calculating the offset of the pointer that jumps over domain name bytes in DNS response packets when a name lacks this termination, and eventually leads to dereferencing the pointer at an invalid/arbitrary address, within newdata() and parse_name() in resolv.c.

## Which versions are affected by CVE-2020-17440?

It affects 1 product.


Products: Uip Project Uip.

## How do I fix CVE-2020-17440?

No fix has been published for CVE-2020-17440 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-17440 being exploited?

There is no known exploitation of CVE-2020-17440 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2020-17438](https://insights.sbomify.com/CVE-2020-17438/): Memory corruption in n/a (critical 9.8)
- [CVE-2020-17439](https://insights.sbomify.com/CVE-2020-17439/): Other in n/a (high 8.3)
- [CVE-2020-24334](https://insights.sbomify.com/CVE-2020-24334/): Denial of service in n/a (high 8.2)
- [CVE-2020-24335](https://insights.sbomify.com/CVE-2020-24335/): Memory corruption in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-17440 and fix it if it is affected.

What it is: CVE-2020-17440 is a high-severity 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-2020-17440 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-2020-17440/ (Markdown: https://insights.sbomify.com/CVE-2020-17440/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-17440
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-17440
- OSV: https://osv.dev/vulnerability/CVE-2020-17440

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-17440/
Summaries are generated and may contain mistakes; the official description above is the record.