PeerTube is an ActivityPub-federated video streaming platform. Prior to 8.2.2, server-side-rendered video watch pages embed a schema.org JSON-LD block by JSON.stringify-ing video metadata without escaping less-than, greater-than, or slash characters, allowing a value containing the byte sequence that closes a script element to inject arbitrary HTML or JavaScript that executes in the instance origin for visitors to the attacker's videos. This issue is fixed in version 8.2.2.
Exploitability
AV:NAC:LAT:NPR:LUI:PVulnerable System
VC:NVI:NVA:NSubsequent System
SC:LSI:LSA:N5.1/CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:NOther