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.
CVSS breakdown
CVSS 3.1
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None
Affected products
- mastodon / mastodon>= 4.5.0-beta.1, < 4.5.11 – >= 4.5.0-beta.1, < 4.5.11
- mastodon / mastodon>= 4.3.0, < 4.4.18 – >= 4.3.0, < 4.4.18