Vulnerabilities in pkg:pypi/matrix-synapse

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6qf2-7x63-mm6v",
  "modified" : "2026-06-09T10:18:35Z",
  "published" : "2026-05-14T16:18:46Z",
  "aliases" : [ "CVE-2026-45076" ],
  "summary" : "Synapse pagination Denial of Service",
  "details" : "### Impact\n\nIn federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients.\n\nClients could therefore fail to display room history.\n\n### Patches\n\nUpdate to Synapse 1.152.1 or later.\n\n### Workarounds\n\nThere are no known workarounds for this issue.\n\n### Identifiers\n\n- ELEMENTSEC-2025-1636\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_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "matrix-synapse"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.152.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/element-hq/synapse/security/advisories/GHSA-6qf2-7x63-mm6v"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-45076"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/element-hq/synapse"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2026-194.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-14T16:18:46Z",
    "nvd_published_at" : "2026-05-28T17:16:31Z"
  }
}