CVE-2022-41952 | Uncontrolled Resource Consumption in Matrix Synapse

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.

Published: 2022-11-22 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2022-41952 is rated Moderate Risk (44.7/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.83%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2022-41952

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.55% 0.83% +0.27%
2 2026-05-18 0.53% 0.55% +0.02%
3 2025-11-23 — 0.53% —

Full EPSS history (14 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2022-41952

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 2.5 [email protected]
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]

Weakness enumeration for CVE-2022-41952

GitHub Security Advisory for CVE-2022-41952

GHSA-4822-jvwx-w47h · Severity: medium · Ecosystem: pip — Uncontrolled Resource Consumption in Matrix Synapse

OS Trackers for CVE-2022-41952

vendor priority summary link
alpine medium CVE-2022-41952: 1 source package rows (synapse); 14 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 14. https://security.alpinelinux.org/vuln/CVE-2022-41952
debian not yet assigned CVE-2022-41952 not yet assigned priority: Debian including 1 source packages (matrix-synapse), 2 status rows across 2 suites (forky, sid): resolved 2. https://security-tracker.debian.org/tracker/CVE-2022-41952
ubuntu medium CVE-2022-41952 medium priority: Ubuntu including 1 source packages (matrix-synapse), 11 status rows across 11 suites (bionic, focal, jammy, kinetic, lunar, mantic, noble, oracular, trusty, upstream, xenial): not-affected 6, ignored 2, needs-triage 2, released 1. https://ubuntu.com/security/CVE-2022-41952

Affected software / configurations for CVE-2022-41952

Vendor Product Version Raw CPE
matrix synapse < 1.53.0 cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*

References for CVE-2022-41952

cvelogic Threat Intelligence