The vulnerabilities, which Siemens self-reported, could allow an attacker to obtain sensitive information or write arbitrary files outside the intended download directory.
.NET Client Library for SIMATIC S7 Webserver API is an official, Siemens-maintained C# library designed to simplify communication between .NET applications and the integrated web servers of SIMATIC S7-1200 and S7-1500 PLCs
The following versions of Siemens SIMATIC S7 Webserver API suffer from the vulnerabilities:
- .NET Client Library for SIMATIC S7 Webserver API version up to 3.3.61
- .NET Client Library for SIMATIC S7 Webserver API version up to 3.3.62
In one issue, affected applications do not properly validate filenames received from remote servers during ticket downloads. This could allow an attacker who can manipulate the ticket response to write arbitrary files outside the intended download directory and, when overwriting ends up enabled, replace existing files accessible to the application.
CVE-2026-85114 is the case number for the vulnerability, which has a CVSS V3 base score of 7.5.
Affected applications do not properly redact PLC restore passwords from HTTP error exception messages. This could allow an attacker with access to logs or other diagnostic output to obtain the plaintext restore password and potentially perform unauthorized operations on the PLC.
CVE-2026-85115 is the case number for the vulnerability, which has a CVSS V3 base score of 5.5.
Industrial Sectors
The product sees use in the critical manufacturing, transportation systems, energy, healthcare and public health, financial services, and government services and facilities sectors. It also sees action on a global basis.
In terms of mitigations:
- For CVE-2026-85114 .NET Client Library for SIMATIC S7 Webserver API up to version V3.3.61, update to V3.3.61 or later
- For CVE-2026-85115 .NET Client Library for SIMATIC S7 Webserver API up to version V3.3.61, update to V3.3.62 or later
- For CVE-2026-85115 .NET Client Library for SIMATIC S7 Webserver API up to version V3.3.62, update to V3.3.62 or later
As a general security measure, Siemens recommends to protect network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends to configure the environment according to Siemens’ operational guidelines for Industrial Security.Â
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