Critical authentication bypass flaw reported in Siemens TeleControl Server Basic
Take action: If you're using Siemens TeleControl Server Basic V3.1, make sure it's isolated from the internet and accessible only from trusted networks. Then plan an update to V3.1.2.3 or later, or restrict access to port 8000 as a temporary workaround since an attacker can steal legitimate passwords and log in.
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Siemens has patched a critical security vulnerability in its TeleControl Server Basic product that could allow unauthenticated remote attackers to obtain password hashes and perform unauthorized database operations.
The vulnerability is tracked as CVE-2025-40765 (CVSS score 9.3), a Missing Authentication for Critical Function vulnerability that enables attackers to bypass authentication mechanisms entirely, gaining access to sensitive password hashes of legitimate users. Once obtained, these credentials can be used to authenticate to the database service and execute operations with full privileges, potentially leading to complete system compromise.
The vulnerability impacts Siemens TeleControl Server Basic V3.1, version V3.1.2.2 and all subsequent versions up to V3.1.2.3. The TeleControl Server Basic is utilized in critical manufacturing sectors and is deployed worldwide, with Siemens headquartered in Germany.
Siemens TeleControl Server Basic V3.1 version V3.1.2.3 and later versions are not affected by this vulnerability. Organizations running vulnerable versions should update as soon as possible
Organizations unable to immediately update to version V3.1.2.3 or later should restrict access to port 8000 on affected systems, limiting connectivity to trusted IP addresses.
