Matrix is an ecosystem for open federated Instant Messaging and VoIP. Synapse is a reference "homeserver" implementation of Matrix. A malicious or poorly-implemented homeserver can inject malformed events into a room by specifying a different room id in the path of a `/send_join`, `/send_leave`, `/invite` or `/exchange_third_party_invite` request. This can lead to a denial of service in which future events will not be correctly sent to other servers over federation. This affects any server which accepts federation requests from untrusted servers. The Matrix Synapse reference implementation before version 1.23.1 the implementation is vulnerable to this injection attack. Issue is fixed in version 1.23.1. As a workaround homeserver administrators could limit access to the federation API to trusted servers (for example via `federation_domain_whitelist`).

Upstream release notes:
https://github.com/matrix-org/synapse/blob/master/CHANGES.md#synapse-1 240rc1-2020-12-02 This release includes some minor changes which may affect homeserver admins:
https://github.com/matrix-org/synapse/blob/develop/UPGRADE.rst#upgradi ng-to-v1240

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website.
Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Matrix developers reports :

A malicious or poorly-implemented homeserver can inject malformed events into a room by specifying a different room id in the path of a /send_join, /send_leave, /invite or /exchange_third_party_invite request. This can lead to a denial of service in which future events will not be correctly sent to other servers over federation. This affects any server which accepts federation requests from untrusted servers.

ID	Name	Product	Family	Severity
144480	Fedora 33 : matrix-synapse (2020-eeb66c2ece)	Nessus	Fedora Local Security Checks	medium
144475	Fedora 32 : matrix-synapse (2020-a2172c484d)	Nessus	Fedora Local Security Checks	medium
144167	FreeBSD : py-matrix-synapse -- DoS on Federation API (cfa0be42-3cd7-11eb-9de7-641c67a117d8)	Nessus	FreeBSD Local Security Checks	medium

Detections

Analytics

CVE-2020-26257

medium

Tenable Plugins

medium

medium

medium