Uncontrolled Resource Consumption in Matrix Synapse
Impact
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.
Patches
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.
We recommend upgrading to 1.53.0 to fully resolve the issue.
Workarounds
Turn off URL preview functionality by setting url_preview_enabled: false in the Synapse configuration file.
References
- Patch (timeout): https://github.com/matrix-org/synapse/pull/11784
- Patch (content type allow list): https://github.com/matrix-org/synapse/pull/11936
For more information
If you have any questions or comments about this advisory, e-mail us at security@matrix.org.
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Python (PyPI) | matrix-synapse | < 1.53.0 | 1.53.0 |
Referencias
- https://github.com/matrix-org/synapse/security/advisories/GHSA-4822-jvwx-w47h
- https://nvd.nist.gov/vuln/detail/CVE-2022-41952
- https://github.com/matrix-org/synapse/pull/11784
- https://github.com/matrix-org/synapse/pull/11936
- https://github.com/matrix-org/synapse
- https://github.com/matrix-org/synapse/releases/tag/v1.52.0
- https://github.com/matrix-org/synapse/releases/tag/v1.53.0
- https://pypi.org/project/matrix-synapse
- https://github.com/advisories/GHSA-4822-jvwx-w47h
- Vector CVSS
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L- Debilidad (CWE)
CWE-400, CWE-772- Plataforma
- Python (PyPI)
- Paquete
matrix-synapse- Publicada
- 01.04.2022
- Actualizado
- 11.10.2026 13:17
Fuentes y licencias
OSV / GitHub Advisory Database - PYSEC-2026-663 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-4822-jvwx-w47h - CC BY 4.0
Historial de vulnerabilidades: matrix-synapse
Todas las vulnerabilidades publicadas de este paquete (Python (PyPI)), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 45
- Primera → última
- 03.2019 05.2026
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Alta 21
- Media 21
- Baja 3
Divulgaciones por año
- 2019: 3
- 2020: 3
- 2021: 12
- 2022: 7
- 2023: 9
- 2024: 7
- 2025: 2
- 2026: 2
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