CVE-2026-41259

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.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/mastodon/mastodon/security/advisories/GHSA-5r37-qpwq-2jhh	Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:joinmastodon:mastodon::::::::
	cpe:2.3:a:joinmastodon:mastodon::::::::
	cpe:2.3:a:joinmastodon:mastodon::::::::

History

28 Apr 2026, 18:50

Type	Values Removed	Values Added
First Time		Joinmastodon mastodon Joinmastodon
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 7.5
CPE		cpe:2.3:a:joinmastodon:mastodon::::::::
References	~~() https://github.com/mastodon/mastodon/security/advisories/GHSA-5r37-qpwq-2jhh -~~	() https://github.com/mastodon/mastodon/security/advisories/GHSA-5r37-qpwq-2jhh - Vendor Advisory

23 Apr 2026, 19:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-04-23 19:17

Updated : 2026-04-28 18:50

NVD link : CVE-2026-41259

Mitre link : CVE-2026-41259

CVE.ORG link : CVE-2026-41259

JSON object : View

Products Affected

joinmastodon

mastodon

CWE

CWE-841

Improper Enforcement of Behavioral Workflow

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