CVE-2026-50128

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.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/mastodon/mastodon/security/advisories/GHSA-rwcw-vq68-g34p
https://github.com/gogs/gogs/security/advisories/GHSA-pwx3-qcgw-vh7h

Configurations

No configuration.

History

No history.

Information

Published : 2026-06-24 21:16

Updated : 2026-06-25 16:32

NVD link : CVE-2026-50128

Mitre link : CVE-2026-50128

CVE.ORG link : CVE-2026-50128

JSON object : View

Products Affected

No product.

CWE

CWE-354

Improper Validation of Integrity Check Value

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