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CVE-2020-26257

Published: 9 December 2020

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`).

Priority

Medium

Cvss 3 Severity Score

6.5

Score breakdown

Status

Package Release Status
matrix-synapse
Launchpad, Ubuntu, Debian
bionic Needs triage

kinetic Ignored
(end of life, was needs-triage)
impish Ignored
(end of life)
focal Needs triage

groovy Ignored
(end of life)
hirsute Ignored
(end of life)
jammy Needs triage

lunar Not vulnerable
(1.64.0-3)
trusty Does not exist

upstream
Released (1.24.0-1)
xenial Does not exist

mantic Not vulnerable
(1.64.0-3)

Severity score breakdown

Parameter Value
Base score 6.5
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact None
Availability impact High
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H