Mastodon: Spoofing of attribution domains_CVE-2026-50128

5.3 / 10

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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.

Basic Information

ID CVE-2026-50128

Source GitHub_M

Published Jun 24, 2026 at 19:48

Affected Product

Vendor mastodon

Product mastodon

Version >= 4.5.0-beta.1, < 4.5.11

Affected Versions mastodon mastodon >= 4.5.0-beta.1, < 4.5.11
mastodon mastodon >= 4.3.0, < 4.4.18

CWE Classification

CWE-354

References

github.com /mastodon/mastodon/security/advisories/GHSA-rwcw-vq68-g34p

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