Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.
Exploitability
AV:NAC:LAT:NPR:HUI:NVulnerable System
VC:NVI:NVA:LSubsequent System
SC:NSI:NSA:N5.1/CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:NInput Validation