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Medium

Synapse unauthenticated writes to the media repository allow planting of problematic content

Type: advisorySources: OSV

Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2024-37303
Confirmed fixed CVEs
Not specified
Updated in this feed
2 Nov 2026, 21:28 UTC · Revision 1

Source evidence

Synapse unauthenticated writes to the media repository allow planting of problematic content

core-osv · Original source

Published 3 Dec 2024, 17:06 UTC

Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.

osv:CVE-2024-37303
Complete source record
{
  "id": "487dd02ce17ee6c3dcb3b83ece7b0ba0a9d64578799e3cceef550257812cb84a",
  "url": "https://osv.dev/vulnerability/CVE-2024-37303",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Synapse unauthenticated writes to the media repository allow planting of problematic content",
    "summary": "Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.",
    "evidence": "osv:CVE-2024-37303",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2024-37303",
      "aliases": [
        "CVE-2024-37303",
        "GHSA-gjgr-7834-rhxr",
        "PYSEC-2024-287"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/element-hq/synapse",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "e26673fe971a4d0316723b0e9ab487297db359f2"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.106"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.106.0rc1",
            "v1.105.0rc1",
            "v1.104.0rc1",
            "v1.103.0rc1",
            "v1.101.0rc1",
            "v1.100.0rc3",
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-37303.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:23.715496975Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/37xxx/CVE-2024-37303.json",
        "https://github.com/element-hq/synapse/security/advisories/GHSA-gjgr-7834-rhxr",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-37303",
        "https://github.com/matrix-org/matrix-spec-proposals/pull/3916"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-306"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/37xxx/CVE-2024-37303.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-37303",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 490241,
  "published_at": "2024-12-03T17:06:02.467+00:00"
}