CISA 2026-10-22

Siemens SIMATIC S7 Webserver API

Machine-generated analysis · WAYSCloud LLM

Versions of the .NET Client Library for SIMATIC S7 Webserver API prior to 3.3.61 are vulnerable to path-traversal and information-leak flaws. Siemens advises updating to version 3.3.61 or newer.

Context

The advisory concerns the .NET Client Library for SIMATIC S7 Webserver API, a component used with Siemens SIMATIC S7 controllers. Versions earlier than 3.3.61 contain path-traversal and error-message information-leak vulnerabilities that could allow arbitrary file writes outside the intended download directory. The advisory notes the product is deployed worldwide across multiple critical infrastructure sectors.

Operator considerations

Check: Verify which systems are running the .NET Client Library for SIMATIC S7 Webserver API and record their version numbers.
Patch: Apply the Siemens-provided update to version 3.3.61 or later.
Log: Monitor for unexpected file writes outside the download directory and for error messages that may expose sensitive information.

From Cybersecurity and Infrastructure Security Agency ↗

.NET Client Library for SIMATIC S7 Webserver API contains multiple vulnerabilities that could allow an attacker to obtain sensitive information or write arbitrary files outside the intended download directory. Siemens has released a new version for .NET Client Library for SIMATIC S7 Webserver API and recommends to update to the latest version.

The following versions of Siemens SIMATIC S7 Webserver API are affected:

.NET Client Library for SIMATIC S7 Webserver API vers:intdot/

Read the full advisory on CISA →