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.
History

Tue, 28 Apr 2026 19:00:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N'}


Tue, 28 Apr 2026 09:00:00 +0000

Type Values Removed Values Added
First Time appeared Joinmastodon
Joinmastodon mastodon
Vendors & Products Joinmastodon
Joinmastodon mastodon

Thu, 23 Apr 2026 20:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 23 Apr 2026 19:15:00 +0000

Type Values Removed Values Added
Description 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.
Title Mastodon: Insufficient verification of email addresses
Weaknesses CWE-841
References
Metrics cvssV4_0

{'score': 8.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-04-23T18:55:20.854Z

Updated: 2026-04-23T19:24:15.567Z

Reserved: 2026-04-18T14:01:46.801Z

Link: CVE-2026-41259

cve-icon Vulnrichment

Updated: 2026-04-23T19:24:12.583Z

cve-icon NVD

Status : Analyzed

Published: 2026-04-23T19:17:30.027

Modified: 2026-04-28T18:50:54.427

Link: CVE-2026-41259

cve-icon Redhat

No data.