As of January 10, 2023, CISA will no longer be updating ICS security advisories for Siemens product vulnerabilities beyond the initial advisory. For the most up-to-date information on vulnerabilities in this advisory, please see Siemens' ProductCERT Security Advisories (CERT Services | Services | Siemens Global).
Successful exploitation of this vulnerability could allow an attacker to cause the application to allocate exhaustive amounts of memory and subsequently create a denial-of-service condition.
Siemens reports that the following products are affected:
The affected product does not properly validate a length field in a serialized message, which it uses to determine the amount of memory to be allocated for deserialization. This could allow an unauthenticated remote attacker to cause the application to allocate exhaustive amounts of memory and subsequently create a partial denial-of-service condition. Successful exploitation is only possible in redundant TeleControl Server Basic setups and only if the connection between the redundant servers has been disrupted.
CVE-2025-29931 has been assigned to this vulnerability. A CVSS v3.1 base score of 3.7 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L ).
A CVSS v4 score has also been calculated for CVE-2025-29931. A base score of 6.3 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N ).
Jin Huang from ADLab of Venustech coordinated this vulnerability with Siemens.
Siemens has released a new version for TeleControl Server Basic and recommends to update to the latest version.
Siemens has identified the following specific workarounds and mitigations users can apply to reduce risk:
As a general security measure, Siemens recommends protecting network access to devices with appropriate mechanisms. To operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemens' operational guidelines for industrial security and following recommendations in the product manuals.
Additional information on industrial security by Siemens can be found on the Siemens industrial security webpage.
For more information see the associated Siemens security advisory SSA-395348 in HTML and CSAF.
CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability, such as:
CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.
CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.
CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.
Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov in the technical information paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies.
Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.
No known public exploitation specifically targeting this vulnerability has been reported to CISA at this time. This vulnerability has a high attack complexity.