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.
https://github.com/matrix-org/synapse/releases/tag/v1.5.0
https://github.com/matrix-org/synapse/pull/6262
Source: Mitre, NVD
Published: 2019-11-08
Updated: 2020-08-24
Base Score: 7.5
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P
Severity: High
Base Score: 9.8
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity: Critical