CVE-2026-22245 Mastodon has SSRF Protection bypass
Attackers can bypass SSRF protections to access local network resources via crafted IP addresses in Mastodon.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-22245?
CVE-2026-22245 is a high-severity server-side request forgery vulnerability in mastodon, published on 8 Jan 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Mastodon is a free, open-source social network server based on ActivityPub. By nature, Mastodon performs a lot of outbound requests to user-provided domains. Mastodon, however, has some protection mechanism to disallow requests to local IP addresses (unless specified in `ALLOWED_PRIVATE_ADDRESSES`) to avoid the "confused deputy" problem. The list of disallowed IP address ranges was lacking some IP address ranges that can be used to reach local IP addresses. An attacker can use an IP address in the affected ranges to make Mastodon perform HTTP requests against loopback or local network hosts, potentially allowing access to otherwise private resources and services. This is fixed in Mastodon v4.5.4, v4.4.11, v4.3.17 and v4.2.29.
Weakness: CWE-918
Which versions are affected by CVE-2026-22245?
1 open source package ship an affected version, including mastodon. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
mastodon Bitnami | All versions | 4.2.29, 4.3.17, 4.4.11, 4.5.4 |
Products include Joinmastodon Mastodon.
How do I fix CVE-2026-22245?
Upgrade mastodon to a fixed version for your release line: 4.2.29, 4.3.17, 4.4.11 or 4.5.4.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-22245 being exploited?
There is no known exploitation of CVE-2026-22245 in the wild and no public exploit code.
Other vulnerabilities in mastodon
- CVE-2023-36460 Mastodon vulnerable to arbitrary file creation through media attachments
- CVE-2022-2166 Improper Restriction of Excessive Authentication Attempts in mastodon/mastodon
- CVE-2022-24307 Missing authorization in n/a
- CVE-2018-21018 Auth bypass in n/a
- CVE-2024-23832 Mastodon Remote user impersonation and takeover
Sources
Also known as BIT-mastodon-2026-22245, GHSA-xfrj-c749-jxxq.