Security advisory

{
  "id": "f2fd0df047053061a016d4e11749c377bb2883b01632aef7c990aa2a45b2fe41",
  "url": "https://osv.dev/vulnerability/CVE-2021-29431",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-29431",
    "summary": "Sydent is a reference Matrix identity server. Sydent can be induced to send HTTP GET requests to internal systems, due to lack of parameter validation or IP address blacklisting. It is not possible to exfiltrate data or control request headers, but it might be possible to use the attack to perform an internal port enumeration. This issue has been addressed in in 9e57334, 8936925, 3d531ed, 0f00412. A potential workaround would be to use a firewall to ensure that Sydent cannot reach internal HTTP resources.",
    "evidence": "osv:CVE-2021-29431",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2021-29431",
      "aliases": [
        "CVE-2021-29431",
        "GHSA-9jhm-8m8c-c3f4",
        "PYSEC-2021-22"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/matrix-org/sydent",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "c2ab10897500dbba1c0d4be33f42985d81bbad7d"
                },
                {
                  "fixed": "0f00412017f25619bc36c264b29ea96808bf310a"
                },
                {
                  "fixed": "3d531ed50d2fd41ac387f36d44d3fb2c62dd22d3"
                },
                {
                  "fixed": "8936925f561b0c352c2fa922d5097d7245aad00a"
                },
                {
                  "fixed": "9e573348d81df8191bbe8c266c01999c9d57cd5f"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:matrix:sydent:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.3.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "0f00412017f25619bc36c264b29ea96808bf310a"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "3d531ed50d2fd41ac387f36d44d3fb2c62dd22d3"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "8936925f561b0c352c2fa922d5097d7245aad00a"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "9e573348d81df8191bbe8c266c01999c9d57cd5f"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "c2ab10897500dbba1c0d4be33f42985d81bbad7d"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v2.3.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "fosdem_2021-01-15",
            "v2.2.0",
            "v2.1.0",
            "v2.0.1",
            "v2.0.0",
            "v1.0.3",
            "v1.0.1",
            "v1.0.2",
            "v1.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-29431.json"
          }
        }
      ],
      "modified": "2026-10-20T10:54:37.117779340Z",
      "provider": "osv",
      "references": [
        "https://github.com/matrix-org/sydent/releases/tag/v2.3.0",
        "https://github.com/matrix-org/sydent/commit/0f00412017f25619bc36c264b29ea96808bf310a",
        "https://github.com/matrix-org/sydent/commit/3d531ed50d2fd41ac387f36d44d3fb2c62dd22d3",
        "https://github.com/matrix-org/sydent/commit/8936925f561b0c352c2fa922d5097d7245aad00a",
        "https://github.com/matrix-org/sydent/commit/9e573348d81df8191bbe8c266c01999c9d57cd5f",
        "https://github.com/matrix-org/sydent/security/advisories/GHSA-9jhm-8m8c-c3f4",
        "https://pypi.org/project/matrix-sydent/"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-29431",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 385749,
  "published_at": "2021-04-15T21:15:17.52+00:00"
}