Server-Side Request Forgery (SSRF) in Mastodon - CVE-2026-46348
Published: May 23, 2026
Vulnerability identifier: #VU132181
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-46348
CWE-ID: CWE-918
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Mastodon
Affected software:
Mastodon
Mastodon
Detailed vulnerability description
The vulnerability allows a remote attacker to access otherwise private resources and services via server-side request forgery.
The vulnerability exists due to improper restriction of requests in outbound request handling when processing user-provided domains. A remote attacker can supply an IPv6 unspecified address (::) to make Mastodon perform HTTP requests against loopback interfaces to access otherwise private resources and services via server-side request forgery.
How to mitigate CVE-2026-46348
Install security update from vendor's website.