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Medium

Synapse vulnerable to leak of remote user device information

Type: advisorySources: OSV

Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2023-43796
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 15:53 UTC · Revision 1

Source evidence

Synapse vulnerable to leak of remote user device information

core-osv · Original source

Published 31 Oct 2023, 16:52 UTC

Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.

osv:CVE-2023-43796
Complete source record
{
  "id": "eb0d1147642d2e41130b3316eb1028a8bf09b066468c98352dc6b7889de3e4b6",
  "url": "https://osv.dev/vulnerability/CVE-2023-43796",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Synapse vulnerable to leak of remote user device information",
    "summary": "Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.",
    "evidence": "osv:CVE-2023-43796",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2023-43796",
      "aliases": [
        "CVE-2023-43796",
        "GHSA-mp92-3jfm-3575",
        "PYSEC-2023-230"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/matrix-org/synapse",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "a11511954a58975d2e5400257a0cecfd27413447"
                },
                {
                  "fixed": "daec55e1fe120c564240c5386e77941372bf458f"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.95.1"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "daec55e1fe120c564240c5386e77941372bf458f"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.95.0",
            "v1.95.0rc1",
            "v1.94.0rc1",
            "v1.90.0rc1",
            "v1.88.0rc1",
            "v1.87.0rc1",
            "v1.84.0rc1",
            "v1.81.0rc1",
            "v1.79.0rc1",
            "v1.78.0rc1",
            "v1.76.0rc1",
            "v1.75.0rc1",
            "v1.63.0rc1",
            "v1.62.0rc1",
            "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-2023-43796.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:30.326090949Z",
      "provider": "osv",
      "references": [
        "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2IDEEZMFJBDLTFHQUTZRJJNCOZGQ2ZVS/",
        "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VH3RNC5ZPQZ4OKPSL4E6BBJSZOQLGDEY/",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/43xxx/CVE-2023-43796.json",
        "https://github.com/matrix-org/synapse/security/advisories/GHSA-mp92-3jfm-3575",
        "https://nvd.nist.gov/vuln/detail/CVE-2023-43796",
        "https://security.gentoo.org/glsa/202401-12",
        "https://github.com/matrix-org/synapse/commit/daec55e1fe120c564240c5386e77941372bf458f"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-200"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/43xxx/CVE-2023-43796.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2023-43796",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 497035,
  "published_at": "2023-10-31T16:52:48.505+00:00"
}