Matrix Synapse before 1.5.0 mishandles signature checking on some federation APIs. Events sent over /send_join, /send_leave, and /invite may not be correctly signed, or may not come from the expected servers.
{
"severity": "HIGH",
"github_reviewed": true,
"github_reviewed_at": "2022-09-19T19:32:08Z",
"nvd_published_at": "2019-11-08T00:15:00Z",
"cwe_ids": [
"CWE-347"
]
}