{"id":"BIT-mastodon-2026-50128","summary":"Mastodon: Spoofing of attribution domains","details":"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.","aliases":["CVE-2026-50128"],"modified":"2026-07-06T08:00:28.561866568Z","published":"2026-07-06T05:55:21.880Z","database_specific":{"severity":"Medium","cpes":["cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*"]},"references":[{"type":"WEB","url":"https://github.com/gogs/gogs/security/advisories/GHSA-pwx3-qcgw-vh7h"},{"type":"WEB","url":"https://github.com/mastodon/mastodon/security/advisories/GHSA-rwcw-vq68-g34p"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-50128"}],"affected":[{"package":{"name":"mastodon","ecosystem":"Bitnami","purl":"pkg:bitnami/mastodon"},"ranges":[{"type":"SEMVER","events":[{"introduced":"4.3.0"},{"fixed":"4.4.18"},{"introduced":"4.5.0"},{"fixed":"4.5.11"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/mastodon/BIT-mastodon-2026-50128.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"}]}],"schema_version":"1.7.5"}