# CVE-2022-31052: matrix-synapse: Synapse is an open source home server implementation for the Matrix chat network

CVE-2022-31052 is fixed in matrix-synapse on 1 platform by DEBIAN-CVE-2022-31052 (version 1.61.1-1), released June 28, 2022. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-31052
- Priority: Routine
- CVSS: 6.5 (medium)
- EPSS: 0.0166
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 28, 2022

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | matrix-synapse Debian 14 | 1.61.1-1 | [DEBIAN-CVE-2022-31052](https://patchblox.com/security/data/fix/linux/debian-cve-2022-31052.md) | Jun 28, 2022 |

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