SSH.NET: ScpClient Recursive Download Allows Arbitrary File Write via Server-Controlled SCP Filenames

{
  "id": "bc646766ad2241a0be5f0d730582fbb2525f22ee8a3738a4d4b537759e811b1a",
  "url": "https://osv.dev/vulnerability/CVE-2026-48798",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "SSH.NET: ScpClient Recursive Download Allows Arbitrary File Write via Server-Controlled SCP Filenames",
    "summary": "SSH.NET is a Secure Shell (SSH) library for .NET. In 2025.1.0 and earlier, ScpClient.Download(string directoryName, DirectoryInfo directoryInfo) trusts file and directory names returned by a remote SCP server and combines them with the requested local directory without containment validation, allowing a malicious, compromised, or man-in-the-middle server to use ../ sequences or absolute paths to create or overwrite files anywhere writable by the client process. This issue is fixed in version 2026.0.0.",
    "evidence": "osv:CVE-2026-48798",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-48798",
      "aliases": [
        "CVE-2026-48798",
        "GHSA-q939-rpr3-3284"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/sshnet/ssh.net",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "7b2fd3dbf2c86a80a7b06cea020aa5f821c9902e"
                },
                {
                  "fixed": "600be0de543765995a189b5d7cd4efac5007f3ce"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2026.0.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "600be0de543765995a189b5d7cd4efac5007f3ce"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "7b2fd3dbf2c86a80a7b06cea020aa5f821c9902e"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "2026.0.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "2025.1.0",
            "2025.0.0",
            "2024.2.0",
            "2024.1.0",
            "2024.0.0",
            "2023.0.1",
            "2023.0.0",
            "2016.1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-48798.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:23.545438774Z",
      "provider": "osv",
      "references": [
        "https://github.com/sshnet/SSH.NET/releases/tag/2026.0.0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48798.json",
        "https://github.com/sshnet/SSH.NET/security/advisories/GHSA-q939-rpr3-3284",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-48798",
        "https://github.com/sshnet/SSH.NET/commit/600be0de543765995a189b5d7cd4efac5007f3ce"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-22",
          "CWE-73"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48798.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-48798",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 490174,
  "published_at": "2026-08-18T14:57:05.059+00:00"
}