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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
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
Which versions are affected by CVE-2026-46348?
1 open source package ship an affected version, including mastodon.
| Package | 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.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-46348 being exploited?
There is no known exploitation of CVE-2026-46348 in the wild and no public exploit code.
Sources
Also known as BIT-mastodon-2026-46348, GHSA-crr4-7rm4-8gpw.