# CVE-2021-3448: Other in dnsmasq

> An attacker can forge DNS replies to poison the cache if dnsmasq is configured with fixed forwarding ports, compromising data integrity.

- **Severity:** Medium 4.0 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 Apr 2021
- **Updated:** 3 Dec 2025
- **Also known as:** ALPINE-CVE-2021-3448, ALSA-2021:4153, CLEANSTART-2026-EO77574, DEBIAN-CVE-2021-3448, GHSA-vvf4-c8p4-89v5, MGASA-2021-0231, OESA-2021-1189, RHSA-2021:4153, RLSA-2021:4153, UBUNTU-CVE-2021-3448, USN-4976-1, USN-4976-2

## What is CVE-2021-3448?

CVE-2021-3448 is a medium-severity vulnerability in Fedoraproject Fedora, published on 8 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw was found in dnsmasq in versions before 2.85. When configured to use a specific server for a given network interface, dnsmasq uses a fixed port while forwarding queries. An attacker on the network, able to find the outgoing port used by dnsmasq, only needs to guess the random transmission ID to forge a reply and get it accepted by dnsmasq. This flaw makes a DNS Cache Poisoning attack much easier. The highest threat from this vulnerability is to data integrity.

Weakness: CWE-358 (Improperly Implemented Security Check for Standard)

## Which versions are affected by CVE-2021-3448?

It affects 4 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `dnsmasq` | AlmaLinux:8 | All versions | 2.79-19.el8 |
| `dnsmasq-utils` | AlmaLinux:8 | All versions | 2.79-19.el8 |
| `dnsmasq` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.79-19.el8 |
| `dnsmasq-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.79-19.el8 |
| `dnsmasq-debugsource` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.79-19.el8 |
| `dnsmasq-utils` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.79-19.el8 |
| `dnsmasq-utils-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.79-19.el8 |
| `dnsmasq` | Rocky Linux:8 | All versions | 0:2.79-19.el8 |

Products: Fedoraproject Fedora, Oracle Communications Cloud Native Core Network Function Cloud Native Environment, Redhat Enterprise Linux, Thekelleys Dnsmasq.

## How do I fix CVE-2021-3448?

Upgrade to a fixed version.

## Is CVE-2021-3448 being exploited?

There is no known exploitation of CVE-2021-3448 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-3448 and fix it if it is affected.

What it is: CVE-2021-3448 is a medium-severity vulnerability in Fedoraproject Fedora, published on 8 Apr 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-2021-3448 in the wild and no public exploit code.

Affected product: Fedoraproject Fedora. 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-2021-3448/ (Markdown: https://insights.sbomify.com/CVE-2021-3448/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3448
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3448
- OSV: https://osv.dev/vulnerability/CVE-2021-3448

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-3448/
Summaries are generated and may contain mistakes; the official description above is the record.