# CVE-2019-9747: Denial of service in n/a

> A malicious mDNS packet causes an infinite loop in the tinysvcmdns library, hanging the server; the project is unmaintained and deprecated.

- **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:** 13 Mar 2019
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-6729-2hp6-xxx8

## What is CVE-2019-9747?

CVE-2019-9747 is a high-severity denial of service vulnerability in n/a, published on 13 Mar 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In tinysvcmdns through 2018-01-16, a maliciously crafted mDNS (Multicast DNS) packet triggers an infinite loop while parsing an mDNS query. When mDNS compressed labels point to each other, the function uncompress_nlabel goes into an infinite loop trying to analyze the packet with an mDNS query. As a result, the mDNS server hangs after receiving the malicious mDNS packet. NOTE: the product's web site states "This project is un-maintained, and has been since 2013. ... There are known vulnerabilities ... You are advised to NOT use this library for any new projects / products."

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2019-9747?

It affects 1 product.


Products: Tinysvcmdns Project Tinysvcmdns.

## How do I fix CVE-2019-9747?

No fix has been published for CVE-2019-9747 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-9747 being exploited?

There is no known exploitation of CVE-2019-9747 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2017-12087](https://insights.sbomify.com/CVE-2017-12087/): Memory corruption in Tinysvcmdns (critical 10.0)
- [CVE-2019-9748](https://insights.sbomify.com/CVE-2019-9748/): Information disclosure in n/a (critical 9.1)
- [CVE-2017-12130](https://insights.sbomify.com/CVE-2017-12130/): Null dereference in Tinysvcmdns (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-9747 and fix it if it is affected.

What it is: CVE-2019-9747 is a high-severity denial of service vulnerability in n/a, published on 13 Mar 2019. 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-2019-9747 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-2019-9747/ (Markdown: https://insights.sbomify.com/CVE-2019-9747/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-9747
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-9747
- OSV: https://osv.dev/vulnerability/CVE-2019-9747

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-9747/
Summaries are generated and may contain mistakes; the official description above is the record.