Arbitrary File Write Vulnerability in SIMATIC S7 Webserver API by Siemens
CVE-2026-85114

8.7HIGH

Key Information:

Vendor

Siemens
Status
.net Client Library For Simatic S7 Webserver Api
Vendor
CVE Published:
13 October 2026

What is CVE-2026-85114?

A vulnerability exists in the .NET Client Library for the SIMATIC S7 Webserver API, specifically in all versions prior to V3.3.61. The issue stems from improper validation of filenames received during ticket downloads from remote servers. As a result, an attacker capable of altering the ticket response may exploit this weakness to write arbitrary files outside the designated download directory. Furthermore, if file overwriting is permitted, this may lead to the replacement of existing critical files, thereby jeopardizing the integrity and security of the application.

Affected Version(s)

.NET Client Library for SIMATIC S7 Webserver API 0

References

https://cert-portal.siemens.com/productcert/html/ssa-3903...

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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