Arch Linux Security Advisory ASA-202011-23 ========================================== Severity: High Date : 2020-11-26 CVE-ID : CVE-2020-26890 Package : matrix-synapse Type : denial of service Remote : Yes Link : https://security.archlinux.org/AVG-1296 Summary ======= The package matrix-synapse before version 1.20.1-1 is vulnerable to denial of service. Resolution ========== Upgrade to 1.20.1-1. # pacman -Syu "matrix-synapse>=1.20.1-1" The problem has been fixed upstream in version 1.20.1. Workaround ========== None. Description =========== Matrix Synapse before 1.20.0 erroneously permits non-standard NaN, Infinity, and -Infinity JSON values in fields of m.room.member events, allowing remote attackers to execute a denial of service attack against the federation and common Matrix clients. If such a malformed event is accepted into the room's state, the impact is long-lasting and is not fixed by an upgrade to a newer version, requiring the event to be manually redacted instead. Since events are replicated to servers of other room members, the impact is not constrained to the server of the event sender. Impact ====== A remote attacker might be able to cause a denial of service via a crafted event. References ========== https://github.com/matrix-org/synapse/security/advisories/GHSA-4mp3-385r-v63... https://github.com/matrix-org/synapse/pull/8106 https://github.com/matrix-org/synapse/pull/8106/commits/c88c15b5fcf26940515b... https://github.com/matrix-org/synapse/pull/8106/commits/248d8284fa850289689f... https://github.com/matrix-org/synapse/pull/8106/commits/5516ae216d8cfe34b04a... https://github.com/matrix-org/synapse/pull/8291 https://github.com/matrix-org/synapse/pull/8291/commits/1cad688bda57dcc8f9c0... https://github.com/matrix-org/synapse/pull/8291/commits/4d654058dec5a77e2d1c... https://security.archlinux.org/CVE-2020-26890