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CVE-2022-41952

MEDIUMCVSS 5.3/10EPSS 0.83%

Last modified

CVE-2022-41952 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. 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). EPSS estimates a 0.83% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1
5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS Probability
0.83%

52.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
MatrixSynapse< 1.53.0

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2022-41952?
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.
How severe is CVE-2022-41952?
CVE-2022-41952 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.83% probability of exploitation in the next 30 days.
How do I fix CVE-2022-41952?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2022-41952?

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Source: NVD / NIST