ghsa-mggc-4xg6-vcxf

{
  "affected": [
    {
      "database_specific": {
        "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-mggc-4xg6-vcxf/GHSA-mggc-4xg6-vcxf.json"
      },
      "package": {
        "ecosystem": "NuGet",
        "name": "SSH.NET",
        "purl": "pkg:nuget/SSH.NET"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2026.0.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2011.12.7",
        "2011.7.29",
        "2011.9.28",
        "2012.12.3",
        "2012.20.12",
        "2012.21.12",
        "2012.3.9",
        "2013.1.27",
        "2013.1.8",
        "2013.4.7",
        "2014.4.6-beta1",
        "2014.4.6-beta2",
        "2016.0.0",
        "2016.0.0-beta1",
        "2016.0.0-beta2",
        "2016.0.0-beta3",
        "2016.1.0",
        "2016.1.0-beta1",
        "2016.1.0-beta2",
        "2016.1.0-beta3",
        "2016.1.0-beta4",
        "2020.0.0",
        "2020.0.0-beta1",
        "2020.0.1",
        "2020.0.2",
        "2023.0.0",
        "2023.0.1",
        "2024.0.0",
        "2024.1.0",
        "2024.2.0",
        "2025.0.0",
        "2025.1.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-85756"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-78"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-17T17:18:01Z",
    "nvd_published_at": "2026-09-16T17:18:16Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\nDefault SCP remote-path handling places caller-supplied paths into the command that runs scp on the server. On a shell-based server that command is interpreted by a shell, so an attacker-influenced path that is not quoted to suit that shell can execute as a command as the authenticated SSH user. SSH.NET provides `ScpClient.RemotePathTransformation` to control escaping behaviour (defaulting to `RemotePathTransformation.DoubleQuote`) but cannot guarantee safety for arbitrary remote command interpreters. This is inherent to running scp over a remote shell (cf. CVE-2020-15778).\n\n## Impact\n\nCommand execution on the SSH server as the authenticated SSH user, when an application passes an attacker-influenced remote path to ScpClient against a shell-based server.\n\nExploitation depends on conditions beyond the attacker's control: the remote server must be shell-based, and the attacker-influenced path must be crafted to defeat the quoting applied by the transformation in effect — that is, to use metacharacters that it does not neutralise (for example $(...) or backticks, which survive the default double-quoting on a POSIX shell). A path that does not meet these escaping rules, or a non-shell-based server, does not result in command execution.\n\n## Remediation\n\nThe fixed release obsoletes the constructors that silently defaulted the path transformation and adds constructors that require an explicit `IRemotePathTransformation`, so callers are required to choose one that suits their server and trust environment. For POSIX shells, the library provides `RemotePathTransformation.ShellQuote`. The legacy default (`RemotePathTransformation.DoubleQuote`) is unchanged for backwards compatibility. SCP is considered legacy and SFTP, which does not involve a remote shell, is recommended where possible (via `SftpClient`).",
  "id": "GHSA-mggc-4xg6-vcxf",
  "modified": "2026-09-17T17:30:05.871228652Z",
  "published": "2026-09-17T17:18:01Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/sshnet/SSH.NET/security/advisories/GHSA-mggc-4xg6-vcxf"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-85756"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sshnet/SSH.NET/commit/c66b9f8fb06c12e71761e58a577b1e796026310f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sshnet/SSH.NET"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sshnet/SSH.NET/releases/tag/2026.0.0"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "SSH.NET: ScpClient allows server-side RCE via default SCP path handling"
}