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CVE-2026-50128 Details

ANALYZED

This CVE record has been analyzed and enriched by NVDAPI.com as an independent party.

Description

Mastodon is a free, open-source social network server based on ActivityPub. From 4.3.0 until 4.5.11 and 4.4.18, Mastodon has a feature to let websites credit authors of their articles. To prevent false attribution claims, Mastodon uses the attributionDomains JSON-LD term, however, an error in how it is defined makes Linked Data Signatures on the toot:attributionDomains property ineffective. An attacker can arbitrarily modify the attributionDomains value of a legitimately signed Update activity and bypass Mastodon’s signature verification. This vulnerability is fixed in 4.5.11 and 4.4.18.

Metrics

CVSS 3.x Severity and Vector Strings:

VolerionCVSS-B:5.3 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CNA: [email protected]CVSS-B:5.3 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://github.com/gogs/gogs/security/advisories/GHSA-pwx3-qcgw-vh7h	CISA-ADP
https://github.com/mastodon/mastodon/security/advisories/GHSA-rwcw-vq68-g34p	[email protected]	AdvisoryRemedyVendor

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-354	Improper Validation of Integrity Check Value	[email protected]

Affected Products

Product	Versions
Mastodon	< 4.5.11 (semver) < 4.4.18 (semver)
CPE No CPEs found in CPE dictionary for this product. Remediation Upgrade: 4.5.11moderate effort Upgrade: 4.4.18moderate effort

Change History

2 change records found show changes

Date	Action	Recorded By
Jun 25, 2026	CVE Modified	CISA-ADP
Jun 24, 2026	New CVE Received	[email protected]