CVE-2021-21273

Published: 26 February 2021

Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.25.0, requests to user provided domains were not restricted to external IP addresses when calculating the key validity for third-party invite events and sending push notifications. This could cause Synapse to make requests to internal infrastructure. The type of request was not controlled by the user, although limited modification of request bodies was possible. For the most thorough protection server administrators should remove the deprecated `federation_ip_range_blacklist` from their settings after upgrading to Synapse v1.25.0 which will result in Synapse using the improved default IP address restrictions. See the new `ip_range_blacklist` and `ip_range_whitelist` settings if more specific control is necessary.

Priority

Cvss 3 Severity Score

6.1

Score breakdown

Status

Package	Release	Status
matrix-synapse Launchpad, Ubuntu, Debian	bionic	Needs triage
	focal	Needs triage
	groovy	Ignored (end of life)
	hirsute	Not vulnerable (1.26.0-3)
	impish	Not vulnerable (1.26.0-3)
	jammy	Not vulnerable (1.26.0-3)
	kinetic	Not vulnerable (1.26.0-3)
	lunar	Not vulnerable (1.26.0-3)
	mantic	Not vulnerable (1.26.0-3)
	trusty	Does not exist
	upstream	Released (1.25.0-1)
	xenial	Does not exist

Severity score breakdown

Parameter	Value
Base score	6.1
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	Required
Scope	Changed
Confidentiality	Low
Integrity impact	Low
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

References

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