CVE-2022-41952Medium· 5.3▾ SunlitUncontrolled Resource Consumption in Matrix Synapse
▾ Sunlit zone — Low / medium · no exploitation signal
impact 29.2 · likelihood 0.2 · exploitation 0
Need a working PoC? Pro members can cast a request and our team develops one — it lands right here.
Exploit-prediction probability, daily snapshots since Jul 8.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
Last analysed / modified upstream
0.8%
0.8% → 0.9%
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.
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.
Turn off URL preview functionality by setting url_preview_enabled: false in the Synapse configuration file.
If you have any questions or comments about this advisory, e-mail us at [email protected].
matrix-synapse < 1.53.0Upgrade to a patched release:
matrix-synapse 1.53.0Connected by shared product, vendor, weakness, or advisory.
CVE-2023-43796Medium· 5.3Synapse vulnerable to leak of remote user device information
CVE-2023-42453Low· 3.1matrix-synapse vulnerable to improper validation of receipts allows forged read receipts
CVE-2023-45129Medium· 4.9matrix-synapse vulnerable to denial of service due to malicious server ACL events
CVE-2023-41335Low· 3.7matrix-synapse vulnerable to temporary storage of plaintext passwords during password changes
CVE-2021-21274Medium· 4.3Denial of service attack via .well-known lookups
CVE-2023-32682Medium· 5.4Synapse has improper checks for deactivated users during login