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-v63f https://github.com/matrix-org/synapse/pull/8106 https://github.com/matrix-org/synapse/pull/8106/commits/c88c15b5fcf26940515b0f6398981ea5fab25347 https://github.com/matrix-org/synapse/pull/8106/commits/248d8284fa850289689f9ae87d2c807b58d7a812 https://github.com/matrix-org/synapse/pull/8106/commits/5516ae216d8cfe34b04ad190d8ec3c50bec07835 https://github.com/matrix-org/synapse/pull/8291 https://github.com/matrix-org/synapse/pull/8291/commits/1cad688bda57dcc8f9c09dff30fcbce818a3a20d https://github.com/matrix-org/synapse/pull/8291/commits/4d654058dec5a77e2d1c50251ac8cd86c2e8e98f https://security.archlinux.org/CVE-2020-26890