CVE-2022-41952

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

0.9% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2022-11-22 16:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 05:04 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.9% in the next 30 days (EPSS).
• Severity: 6.5 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2022-11-22 16:15 UTC

Last modified

2026-06-17 05:04 UTC

Exploit probability

0.9% · EPSS, next 30 days

Weakness

CWE-400 · Uncontrolled resource consumption

Record status

Modified

Affected

• Matrix Synapse < 1.53.0

Attack profile CVSS 3.1 · 6.5

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

Low

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2022-41952.md and follow it. Check whether this project is affected by CVE-2022-41952. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

Copy as ticket · More options · Status badge