high7.5
CVE-2026-41259
Mastodon is a free, open-source social network server based on ActivityPub.
Impact
Mastodon is a free, open-source social network server based on ActivityPub. Prior to v4.5.9, v4.4.16, and v4.3.22, Mastodon allows restricting new user sign-up based on e-mail domain names, and performs basic validation on e-mail addresses, but fails to restrict characters that are interpreted differently by some mailing servers. This vulnerability is fixed in v4.5.9, v4.4.16, and v4.3.22.
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Joinmastodon | Mastodon | before 4.3.22 from 4.4.0 before 4.4.16 from 4.5.0 before 4.5.9 |