{"id":"CVE-2026-50128","aliases":["BIT-mastodon-2026-50128","EUVD-2026-39059"],"status":"published","title":"Mastodon: Spoofing of attribution domains","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.","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00183,"percentile":0.07953,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-354"],"published":"2026-06-24T19:48:52Z","modified":"2026-10-28T02:30:37Z","fixes":[{"ecosystem":"Bitnami","package":"mastodon","fixed_in":["4.4.18","4.5.11"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Bitnami","package":"mastodon","ranges":[{"type":"SEMVER","events":[{"introduced":"4.3.0"},{"fixed":"4.4.18"},{"introduced":"4.5.0"},{"fixed":"4.5.11"}]}]}],"products":[{"vendor":"mastodon","product":"mastodon"}],"references":[{"url":"https://github.com/mastodon/mastodon/security/advisories/GHSA-rwcw-vq68-g34p","tags":["x_refsource_CONFIRM","web","advisory"]},{"url":"https://github.com/gogs/gogs/security/advisories/GHSA-pwx3-qcgw-vh7h","tags":["exploit","web","evidence"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-50128","tags":["web","advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50128.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-50128","title":"Mastodon: Spoofing of attribution domains","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.","status":"published","published":"2026-06-24T19:48:52.942Z","modified":"2026-06-25T15:40:03.219Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-354"],"updated_at":"2026-11-02T14:20:08.734143Z"}],"euvd":[{"id":"EUVD-2026-39059","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.","status":"published","published":"2026-06-24T19:48:52Z","modified":"2026-06-25T15:40:03Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T18:20:25.700423Z"}],"nvd":[{"id":"CVE-2026-50128","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.","status":"published","published":"2026-06-24T21:16:54.89Z","modified":"2026-06-25T16:32:07.257Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-354"],"updated_at":"2026-11-02T14:12:25.67873Z"}],"osv":[{"id":"CVE-2026-50128","title":"Mastodon: Spoofing of attribution domains","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.","status":"published","published":"2026-06-24T19:48:52.942Z","modified":"2026-10-28T02:30:37.387048653Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"cwes":["CWE-354"],"updated_at":"2026-11-02T15:45:07.060148Z"},{"id":"BIT-mastodon-2026-50128","title":"Mastodon: Spoofing of attribution domains","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.","status":"published","published":"2026-07-06T05:55:21.88Z","modified":"2026-07-06T08:00:28.561866568Z","updated_at":"2026-11-02T15:28:32.645004Z"}]}}