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.
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Thu, 25 Jun 2026 16:30:00 +0000
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ssvc
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Thu, 25 Jun 2026 13:30:00 +0000
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Joinmastodon
Joinmastodon mastodon |
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Joinmastodon
Joinmastodon mastodon |
Wed, 24 Jun 2026 20:30:00 +0000
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| 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. | |
| Title | Mastodon: Spoofing of attribution domains | |
| Weaknesses | CWE-354 | |
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cvssV3_1
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Status: PUBLISHED
Assigner: GitHub_M
Published: 2026-06-24T19:48:52.942Z
Updated: 2026-06-25T15:40:03.219Z
Reserved: 2026-06-03T18:49:32.275Z
Link: CVE-2026-50128
Updated: 2026-06-25T15:39:45.433Z
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