CVE-2026-46746: SINEC INS RCE Vulnerability

CVE-2026-46746 Overview

CVE-2026-46746 is a stored command injection vulnerability in Siemens SINEC INS (Infrastructure Network Services) affecting all versions prior to V1.0 SP2 Update 6. The flaw resides in the /api/sftp/uploadFiles endpoint, which fails to sanitize user-supplied directory names. Attackers can inject shell command payloads through crafted directory names. The payloads are stored and later executed when directory listings are retrieved. An authenticated remote attacker can use this flaw to execute arbitrary operating system commands with the privileges of the sinecins service account. The weakness is classified under CWE-78, OS Command Injection.

Critical Impact
Authenticated remote attackers can achieve arbitrary command execution on the underlying operating system, leading to full compromise of confidentiality, integrity, and availability of the SINEC INS host.

Affected Products

Siemens SINEC INS — all versions prior to V1.0 SP2 Update 6
Network infrastructure deployments using SINEC INS SFTP services
Industrial environments running SINEC INS as a centralized network services platform

Discovery Timeline

2026-06-09 - CVE-2026-46746 published to NVD
2026-06-09 - Last updated in NVD database

Technical Details for CVE-2026-46746

Vulnerability Analysis

The vulnerability is a stored OS command injection in the SFTP file upload component of SINEC INS. The /api/sftp/uploadFiles endpoint accepts directory names from authenticated users without proper sanitization. When a directory listing is later requested, the server processes the previously stored directory name in a shell context. Any embedded shell metacharacters or command separators are interpreted by the operating system shell rather than treated as literal filename data. Because execution occurs under the sinecins service account, the attacker inherits that account's permissions over the SINEC INS host.

Root Cause

The root cause is missing input validation and improper neutralization of special elements in shell commands. Directory names supplied through the SFTP upload API are concatenated into shell command strings used during listing operations. Characters such as ;, |, &, `, and $() retain their shell semantics. The application does not enforce an allowlist of permitted filename characters and does not pass user input as separate arguments to a safe execution API. This is a textbook instance of CWE-78.

Attack Vector

Exploitation requires network access to the SINEC INS management interface and valid authenticated credentials with permission to upload files via SFTP. The attacker creates a directory whose name contains shell metacharacters and an embedded command payload. The malicious directory name is stored server-side. When the directory listing endpoint is invoked, the stored payload is passed to the shell and executed as the sinecins user. No user interaction is required to trigger execution beyond the standard listing request. See the Siemens Security Advisory SSA-860189 for vendor-confirmed technical details.

Detection Methods for CVE-2026-46746

Indicators of Compromise

Directory or file entries on the SINEC INS host containing shell metacharacters such as ;, |, `, or $() in their names
Unexpected child processes spawned by the sinecins service account, particularly shells (sh, bash) or networking utilities (curl, wget, nc)
Outbound network connections from the SINEC INS server to unfamiliar external hosts
Anomalous HTTP POST requests to /api/sftp/uploadFiles containing encoded shell syntax in directory name parameters

Detection Strategies

Inspect web server and application logs for /api/sftp/uploadFiles requests carrying suspicious directory name fields
Monitor process creation events where the parent is the SINEC INS service and the child is an interpreter or system binary
Apply CWE-78 detection rules that flag shell metacharacters in API parameters destined for filesystem operations
Review SFTP directory listings for entries that deviate from expected naming conventions

Monitoring Recommendations

Forward SINEC INS application, audit, and OS-level process telemetry to a centralized SIEM for correlation
Alert on any process executed by the sinecins user that is not part of the documented service baseline
Track authentication events to the SINEC INS API and correlate them with subsequent file or directory operations
Establish a baseline of normal /api/sftp/uploadFiles payload structure to surface deviations

How to Mitigate CVE-2026-46746

Immediate Actions Required

Upgrade SINEC INS to V1.0 SP2 Update 6 or later, as directed by Siemens
Restrict network access to the SINEC INS management interface using firewall rules and network segmentation
Audit accounts with SFTP upload privileges and remove unnecessary access
Review historical directory listings and process logs for evidence of prior exploitation

Patch Information

Siemens has released SINEC INS V1.0 SP2 Update 6, which remediates CVE-2026-46746. Customers should obtain the update from Siemens Industry Online Support and apply it on all affected installations. Refer to the Siemens Security Advisory SSA-860189 for the authoritative remediation guidance and download instructions.

Workarounds

Limit access to the SINEC INS SFTP service to trusted operator workstations only
Enforce least-privilege role assignments so that only essential users hold SFTP upload permissions
Place SINEC INS within a dedicated operations network protected by a deny-by-default firewall policy
Monitor the sinecins account closely for unexpected process activity until patching is complete

bash

# Example firewall restriction limiting SINEC INS API access to trusted hosts
iptables -A INPUT -p tcp --dport 443 -s 10.10.20.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP