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CVE-2022-41952

Published: 22 November 2022

Synapse before 1.52.0 with URL preview functionality enabled will attempt to generate URL previews for media stream URLs without properly limiting connection time. Connections will only be terminated after `max_spider_size` (default: 10M) bytes have been downloaded, which can in some cases lead to long-lived connections towards the streaming media server (for instance, Icecast). This can cause excessive traffic and connections toward such servers if their stream URL is, for example, posted to a large room with many Synapse instances with URL preview enabled. Version 1.52.0 implements a timeout mechanism which will terminate URL preview connections after 30 seconds. Since generating URL previews for media streams is not supported and always fails, 1.53.0 additionally implements an allow list for content types for which Synapse will even attempt to generate a URL preview. Upgrade to 1.53.0 to fully resolve the issue. As a workaround, turn off URL preview functionality by setting `url_preview_enabled: false` in the Synapse configuration file.

Priority

Medium

Cvss 3 Severity Score

5.3

Score breakdown

Status

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

focal Needs triage

jammy Not vulnerable
(1.53.0-1)
kinetic Not vulnerable

trusty Ignored
(end of standard support)
upstream
Released (1.53.0-1)
xenial Ignored
(end of standard support)
lunar Not vulnerable

mantic Not vulnerable

Severity score breakdown

Parameter Value
Base score 5.3
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact None
Availability impact Low
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L