Skip to content
Heist/ feed
Back to feed
Medium

Uncontrolled Resource Consumption in Matrix Synapse

Type: advisorySources: OSV

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.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2022-41952
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 05:42 UTC · Revision 1

Source evidence

Uncontrolled Resource Consumption in Matrix Synapse

core-osv · Original source

Published 22 Nov 2022, 00:00 UTC

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.

osv:CVE-2022-41952
Complete source record
{
  "id": "2aee8fa81ff462a0cb167efdf8541002e30901b1c8fe17f142737720147560bc",
  "url": "https://osv.dev/vulnerability/CVE-2022-41952",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Uncontrolled Resource Consumption in Matrix Synapse",
    "summary": "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.",
    "evidence": "osv:CVE-2022-41952",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2022-41952",
      "aliases": [
        "CVE-2022-41952",
        "GHSA-4822-jvwx-w47h",
        "PYSEC-2026-663"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/matrix-org/synapse",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "551dd8c9f8d10681dc535ec43d652bbadf60de48"
                },
                {
                  "fixed": "5cdd4913100961f943f6432d9fbdaa20907142c2"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.53.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "5cdd4913100961f943f6432d9fbdaa20907142c2"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v1.52.0"
                  },
                  {
                    "range": [
                      {
                        "fixed": "551dd8c9f8d10681dc535ec43d652bbadf60de48"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v1.53.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.53.0rc1",
            "v1.52.0rc1",
            "v1.49.0rc1",
            "v1.40.0rc1",
            "v1.36.0rc1",
            "v1.35.0rc1",
            "v1.34.0rc1",
            "v1.32.0rc1",
            "v1.31.0rc1",
            "v1.30.0rc1",
            "v1.29.0rc1",
            "v1.27.0rc1",
            "v1.24.0rc1",
            "v1.23.0rc1",
            "v1.17.0rc1",
            "v1.18.0rc1",
            "v1.16.0rc1",
            "v1.15.0rc1",
            "v1.14.0rc1",
            "v1.12.0rc1",
            "v1.6.0rc1",
            "v1.11.0rc1",
            "v1.3.0rc1",
            "v1.1.0rc2",
            "v1.1.0rc1",
            "v1.10.0rc1",
            "v1.9.0rc1",
            "v1.9.0.dev2",
            "v1.9.0.dev1",
            "v1.8.0rc1",
            "v1.5.0rc1",
            "v1.4.0rc1",
            "v0.99.5.1.dev0",
            "v0.99.4rc1",
            "v0.99.2rc1",
            "v0.99.1rc1",
            "hhs-8",
            "hhs-7",
            "hhs-6",
            "hhs-5",
            "hhs-3",
            "hhs-2",
            "hhs-1",
            "v0.32.2",
            "v0.32.0",
            "v0.32.0rc1",
            "v0.28.0-rc1",
            "v0.25.0-rc1",
            "v0.23.0-rc2",
            "v0.23.0-rc1",
            "v0.18.5",
            "v0.18.4",
            "v0.18.3",
            "v0.18.2",
            "v0.18.1",
            "v0.18.0",
            "v0.17.3",
            "v0.17.2",
            "v0.17.1",
            "v0.17.0",
            "v0.16.1-r1",
            "v0.16.1",
            "v0.16.0",
            "v0.14.0",
            "v0.13.3",
            "v0.13.2",
            "v0.13.1",
            "v0.12.0",
            "v0.11.1",
            "v0.11.0-r2",
            "v0.11.0-r1",
            "v0.11.0",
            "v0.10.0-r2",
            "v0.10.0-r1",
            "v0.10.0",
            "v0.9.3",
            "v0.9.2-r2",
            "v0.9.2-r1",
            "v0.9.2",
            "v0.9.1",
            "v0.9.0-r5",
            "v0.9.0-r4",
            "v0.9.0-r3",
            "v0.9.0-r2",
            "v0.9.0-r1",
            "v0.9.0",
            "v0.8.1-r4",
            "v0.8.1-r3",
            "v0.8.1-r2",
            "v0.8.1-r1",
            "v0.8.1",
            "v0.8.0",
            "v0.7.1-r4",
            "v0.7.1-r3",
            "v0.7.1-r2",
            "v0.7.1-r1",
            "v0.7.1",
            "v0.7.0f",
            "v0.7.0e",
            "v0.7.0d",
            "v0.7.0c",
            "v0.7.0b",
            "v0.7.0a",
            "v0.7.0",
            "v0.6.1f",
            "v0.6.1e",
            "v0.6.1d",
            "v0.6.1c",
            "v0.6.1b",
            "v0.6.1a",
            "v0.6.1",
            "v0.6.0b",
            "v0.6.0a",
            "v0.6.0",
            "v0.5.4a",
            "v0.5.4",
            "v0.5.3c",
            "v0.5.3b",
            "v0.5.3a",
            "v0.5.3",
            "v0.5.2",
            "v0.5.1",
            "v0.5.0",
            "v0.4.2",
            "v0.4.1",
            "v0.3.4",
            "v0.3.3",
            "v0.3.0",
            "v0.2.2",
            "v0.2.1a",
            "v0.2.1",
            "v0.2.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-41952.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:26.498054695Z",
      "provider": "osv",
      "references": [
        "https://github.com/matrix-org/synapse/releases/tag/v1.52.0",
        "https://github.com/matrix-org/synapse/releases/tag/v1.53.0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/41xxx/CVE-2022-41952.json",
        "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"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-400"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/41xxx/CVE-2022-41952.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2022-41952",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 492792,
  "published_at": "2022-11-22T00:00:00+00:00"
}