CVE-2022-31052 Information

Description

Synapse is an open source home server implementation for the Matrix chat network. In versions prior to 1.61.1 URL previews of some web pages can exhaust the available stack space for the Synapse process due to unbounded recursion. This is sometimes recoverable and leads to an error for the request causing the problem but in other cases the Synapse process may crash altogether. It is possible to exploit this maliciously either by malicious users on the homeserver or by remote users sending URLs that a local user’s client may automatically request a URL preview for. Remote users are not able to exploit this directly because the URL preview endpoint is authenticated. Deployments with url_preview_enabled: false set in configuration are not affected. Deployments with url_preview_enabled: true set in configuration are affected. Deployments with no configuration value set for url_preview_enabled are not affected because the default is false. Administrators of homeservers with URL previews enabled are advised to upgrade to v1.61.1 or higher. Users unable to upgrade should set url_preview_enabled to false.

Reference

https://github.com/matrix-org/synapse/security/advisories/GHSA-22p3-qrh9-cx32 https://spec.matrix.org/v1.2/client-server-api/#get_matrixmediav3preview_url https://spec.matrix.org/v1.2/client-server-api/#get_matrixmediav3preview_url https://github.com/matrix-org/synapse/commit/fa1308061802ac7b7d20e954ba7372c5ac292333 Synapse is an open source home server implementation for the Matrix chat network. In versions prior to 1.61.1 URL previews of some web pages can exhaust the available stack space for the Synapse process due to unbounded recursion. This is sometimes recoverable and leads to an error for the request causing the problem but in other cases the Synapse process may crash altogether. It is possible to exploit this maliciously either by malicious users on the homeserver or by remote users sending URLs that a local user’s client may automatically request a URL preview for. Remote users are not able to exploit this directly because the URL preview endpoint is authenticated. Deployments with url_preview_enabled: false set in configuration are not affected. Deployments with url_preview_enabled: true set in configuration are affected. Deployments with no configuration value set for url_preview_enabled are not affected because the default is false. Administrators of homeservers with URL previews enabled are advised to upgrade to v1.61.1 or higher. Users unable to upgrade should set url_preview_enabled to false.