Sign in Sign up
JA · EN · FR
SecPulse
Categories
CVE-2026-85756 high CVSS 7.5

OS Command Injection in SSH.NET (CVE-2026-85756)

Summary

OS command injection in SSH.NET (CVE-2026-85756). Successful exploitation can lead to full system takeover. Exploitable via ScpClient.RemotePathTransformation. Mitigation: upgrade to 2026.0.0 or later.

Original description

The description as published by the source.

Summary

Default 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).

Impact

Command 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.

Exploitation 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.

Remediation

The 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 t…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-85756 has been found in SSH.NET.
Attackers can target a specific entry point like ScpClient.RemotePathTransformation over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 7.5/10.
What to do: upgrade SSH.NET to 2026.0.0 or later.
If unsure, ask your IT team or search "SSH.NET CVE-2026-85756" on the vendor's site.

CVE-2026-85756 (SSH.NET) — CWE-78 / CVSS v3 7.5
Attack vector: remote (network-reachable) / no user interaction
Attack surface: ScpClient.RemotePathTransformation / RemotePathTransformation.DoubleQuote / IRemotePathTransformation / RemotePathTransformation.ShellQuote
Patched: 2026.0.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

OS command injection (CWE-78) exists in SSH.NET. Attackers reach the vulnerable code path via ScpClient.RemotePathTransformation.

📍 Affected scope

Check the vendor advisory for the affected versions of SSH.NET. Attack surface: ScpClient.RemotePathTransformation / RemotePathTransformation.DoubleQuote / IRemotePathTransformation / RemotePathTransformation.ShellQuote.

🔥 Severity

Severity: High (CVSS 7.5/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 2026.0.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'SSH.NET' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'SSH.NET' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で SSH.NET を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade SSH.NET to 2026.0.0

    ステージング環境で 2026.0.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

nuget SSH.NET
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2026.0.0"}]}]

References

We use cookies for analytics and ad measurement. This setting applies to all Game co., Ltd. sites. Details