{
  "schema_version": "1.4.0",
  "id": "GHSA-v56r-hwv5-mxg6",
  "modified": "2025-03-27T18:02:14Z",
  "published": "2025-03-27T18:02:14Z",
  "aliases": [
    "CVE-2025-30355"
  ],
  "summary": "Synapse vulnerable to federation denial of service via malformed events",
  "details": "### Impact\nA malicious server can craft events which, when received, prevent Synapse version up to 1.127.0 from federating with other servers. The vulnerability has been exploited in the wild.\n\n### Patches\nFixed in Synapse v1.127.1.\n\n### Workarounds\nClosed federation environments of trusted servers or non-federating installations are not affected.\n\n### For more information\n\nIf you have any questions or comments about this advisory, please email us at [security at element.io](mailto:security@element.io).",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "matrix-synapse"
      },
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.127.1"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/element-hq/synapse/security/advisories/GHSA-v56r-hwv5-mxg6"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-30355"
    },
    {
      "type": "WEB",
      "url": "https://github.com/element-hq/synapse/commit/2277df2a1eb685f85040ef98fa21d41aa4cdd389"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/element-hq/synapse"
    },
    {
      "type": "WEB",
      "url": "https://github.com/element-hq/synapse/releases/tag/v1.127.1"
    }
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20"
    ],
    "severity": "HIGH",
    "github_reviewed": true,
    "github_reviewed_at": "2025-03-27T18:02:14Z",
    "nvd_published_at": "2025-03-27T01:15:12Z"
  }
}