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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.
Cite this page
CVE-2022-41952. CVEDatabase.com. Retrieved 3 May 2026. https://cvedatabase.com/cve/CVE-2022-41952
Use CWE-400, Matrix vendor hub and Synapse product page to widen CVE-2022-41952 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2024-52815, CVE-2024-53863 and CVE-2024-52805 for nearby disclosures in the same product family.