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

Cvss 3 Severity Score

6.5

Score breakdown

Status

Package	Release	Status
matrix-synapse Launchpad, Ubuntu, Debian	bionic	Needs triage
	focal	Needs triage
	groovy	Ignored (end of life)
	hirsute	Ignored (end of life)
	impish	Ignored (end of life)
	jammy	Needs triage
	kinetic	Ignored (end of life, was needs-triage)
	lunar	Not vulnerable (1.64.0-3)
	mantic	Not vulnerable (1.64.0-3)
	trusty	Does not exist
	upstream	Released (1.24.0-1)
	xenial	Does not exist

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

References

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