CVE-2026-33868 Scanner.
Mastodon - Open Redirect
Free and read-only. Scan only sites you own or are allowed to test.
What This Check Does.
Read-only
It only asks your site for public pages, the way a browser would. Nothing is changed, uploaded or stored.
Up to 1 request
A small, fixed number of requests, so the check is quick and will not load your site.
Looks for CVE-2026-33868
It looks for the specific sign of this one vulnerability and ends with a clear answer: vulnerable, not vulnerable, or could not be determined.
About CVE-2026-33868. What It Means.
Mastodon version < 4.5.8, < 4.4.15, < 4.3.21 is vulnerable to unauthenticated Open Redirect vulnerability (CWE-601) exists in the /web/* route due to improper handling of URL-encoded path segments.
FAQ
Common Questions.
Mastodon - Open Redirect. Mastodon version < 4.5.8, < 4.4.15, < 4.3.21 is vulnerable to unauthenticated Open Redirect vulnerability (CWE-601) exists in the /web/* route due to improper handling of URL-encoded path segments.
Atlas sends up to 1 read-only request to your site and looks for the specific sign of CVE-2026-33868 in Mastodon. Nothing is changed, uploaded or stored on your site.
CVE-2026-33868 is not on the CISA Known Exploited Vulnerabilities list at the time of writing, but it is still worth fixing. Its CVSS score is 4.3.
Yes. The check only reads public pages, the same way a browser or a search engine would. Scan only sites you own or are allowed to test.
It means no sign of CVE-2026-33868 was found by this read-only check. It does not prove the site is free of other weaknesses.
Update Mastodon to the latest version from the vendor, or follow the vendor's advice to switch off the affected feature. The vendor links and details are in the CVE-2026-33868 briefing linked on this page.
Scan only sites you own or have written permission to test. A result of Not Vulnerable means this read-only check found no sign of CVE-2026-33868; it is not a guarantee that the site is secure.