# CVE-2026-46348: Mastodon: SSRF Bypass via IPv6 Unspecified Address (::)

> Attackers can bypass SSRF protections using IPv6 unspecified addresses to access private loopback resources in Mastodon.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Jun 2026
- **Updated:** 25 Jun 2026
- **Also known as:** BIT-mastodon-2026-46348, GHSA-crr4-7rm4-8gpw

## What is CVE-2026-46348?

CVE-2026-46348 is a high-severity server-side request forgery vulnerability in mastodon, published on 24 Jun 2026. 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 4.5.10, 4.4.17, and 4.3.23, the list of disallowed IP address ranges was lacking an IP address range that can be used to reach local IP addresses. An attacker can use an IP address in the affected range to make Mastodon perform HTTP requests against loopback interfaces, potentially allowing access to otherwise private resources and services. This vulnerability is fixed in 4.5.10, 4.4.17, and 4.3.23.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-46348?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mastodon` | Bitnami | From 4.5.0 | 4.5.10 |

## How do I fix CVE-2026-46348?

Upgrade mastodon to 4.5.10 or later.

## Is CVE-2026-46348 being exploited?

There is no known exploitation of CVE-2026-46348 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46348 and fix it if it is affected.

What it is: CVE-2026-46348 is a high-severity server-side request forgery vulnerability in mastodon, published on 24 Jun 2026. 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-2026-46348 in the wild and no public exploit code.

Affected packages and fixed versions:
- mastodon (Bitnami): affected from 4.5.0; fixed in 4.5.10

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-2026-46348/ (Markdown: https://insights.sbomify.com/CVE-2026-46348/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46348
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46348
- OSV: https://osv.dev/vulnerability/CVE-2026-46348

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46348/
Summaries are generated and may contain mistakes; the official description above is the record.