# CVE-2023-42451: Mastodon Invalid Domain Name Normalization vulnerability

> Attackers can spoof domains they do not own by exploiting a flaw in domain name normalization within the Mastodon server.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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:** 19 Sep 2023
- **Updated:** 24 Sep 2024
- **Also known as:** BIT-mastodon-2023-42451, GHSA-v3xf-c9qf-j667

## What is CVE-2023-42451?

CVE-2023-42451 is a high-severity vulnerability in mastodon, published on 19 Sep 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 3.5.14, 4.0.10, 4.1.8, and 4.2.0-rc2, under certain circumstances, attackers can exploit a flaw in domain name normalization to spoof domains they do not own. Versions 3.5.14, 4.0.10, 4.1.8, and 4.2.0-rc2 contain a patch for this issue.

Weakness: CWE-706 (Use of Incorrectly-Resolved Name or Reference)

## Which versions are affected by CVE-2023-42451?

1 open source package ship an affected version, including mastodon. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mastodon` | Bitnami | All versions | 3.5.14, 4.0.10, 4.1.8 |

Products: Joinmastodon Mastodon.

## How do I fix CVE-2023-42451?

Upgrade mastodon to a fixed version for your release line: 3.5.14, 4.0.10 or 4.1.8.

## Is CVE-2023-42451 being exploited?

There is no known exploitation of CVE-2023-42451 in the wild and no public exploit code.

## Other vulnerabilities in mastodon

- [CVE-2023-36460](https://insights.sbomify.com/CVE-2023-36460/): Mastodon vulnerable to arbitrary file creation through media attachments (critical 10.0)
- [CVE-2022-2166](https://insights.sbomify.com/CVE-2022-2166/): Improper Restriction of Excessive Authentication Attempts in mastodon/mastodon (critical 9.8)
- [CVE-2022-24307](https://insights.sbomify.com/CVE-2022-24307/): Missing authorization in n/a (critical 9.8)
- [CVE-2018-21018](https://insights.sbomify.com/CVE-2018-21018/): Auth bypass in n/a (critical 9.8)
- [CVE-2024-23832](https://insights.sbomify.com/CVE-2024-23832/): Mastodon Remote user impersonation and takeover (critical 9.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-42451 and fix it if it is affected.

What it is: CVE-2023-42451 is a high-severity vulnerability in mastodon, published on 19 Sep 2023. 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-2023-42451 in the wild and no public exploit code.

Affected packages and fixed versions:
- mastodon (Bitnami): affected all versions; fixed in 3.5.14, 4.0.10, 4.1.8

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-2023-42451/ (Markdown: https://insights.sbomify.com/CVE-2023-42451/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-42451
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-42451
- OSV: https://osv.dev/vulnerability/CVE-2023-42451

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-42451/
Summaries are generated and may contain mistakes; the official description above is the record.