# CVE-2021-4184: Denial of service in Wireshark

> An infinite loop in the BitTorrent DHT dissector allows attackers to cause a denial of service via crafted packets or files.

- **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:** Yes
- **Published:** 30 Dec 2021
- **Updated:** 3 Nov 2025
- **Also known as:** AZL-7419, DEBIAN-CVE-2021-4184, GHSA-g3fh-c7h3-x56j

## What is CVE-2021-4184?

CVE-2021-4184 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 30 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Infinite loop in the BitTorrent DHT dissector in Wireshark 3.6.0 and 3.4.0 to 3.4.10 allows denial of service via packet injection or crafted capture file

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

## Which versions are affected by CVE-2021-4184?

It affects 5 products.


Products: Debian Debian Linux, Fedoraproject Fedora, Oracle Http Server, Oracle Zfs Storage Appliance Kit, Wireshark Wireshark.

## How do I fix CVE-2021-4184?

Upgrade to a fixed version.

## Is CVE-2021-4184 being exploited?

There is no known exploitation of CVE-2021-4184 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-4184 and fix it if it is affected.

What it is: CVE-2021-4184 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 30 Dec 2021. 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-2021-4184 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2021-4184/ (Markdown: https://insights.sbomify.com/CVE-2021-4184/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-4184
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-4184
- OSV: https://osv.dev/vulnerability/CVE-2021-4184

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-4184/
Summaries are generated and may contain mistakes; the official description above is the record.