Vulnerabilities in pkg:nuget/SSH.NET

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-mggc-4xg6-vcxf",
  "modified" : "2026-09-17T17:18:01Z",
  "published" : "2026-09-17T17:18:01Z",
  "aliases" : [ "CVE-2026-85756" ],
  "summary" : "SSH.NET: ScpClient allows server-side RCE via default SCP path handling",
  "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`).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "SSH.NET"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2026.0.0"
      } ]
    } ]
  } ],
  "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-78" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-17T17:18:01Z",
    "nvd_published_at" : "2026-09-16T17:18:16Z"
  }
}