VDB-308608 · CVE-2025-40556 · ssa-828116

Siemens BACnet ATEC 550-446 MSTP Message denial of service

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.5	$0-$5k	0.00

Summaryinfo

A vulnerability was found in Siemens BACnet ATEC 550-440, BACnet ATEC 550-441, BACnet ATEC 550-445 and BACnet ATEC 550-446. It has been declared as problematic. This vulnerability affects unknown code of the component MSTP Message Handler. Executing a manipulation can lead to denial of service. This vulnerability appears as CVE-2025-40556. The attacker needs to be present on the local network. There is no available exploit.

Detailsinfo

A vulnerability was found in Siemens BACnet ATEC 550-440, BACnet ATEC 550-441, BACnet ATEC 550-445 and BACnet ATEC 550-446 (version now known). It has been declared as critical. This vulnerability affects some unknown processing of the component MSTP Message Handler. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. As an impact it is known to affect availability. CVE summarizes:

A vulnerability has been identified in BACnet ATEC 550-440 (All versions), BACnet ATEC 550-441 (All versions), BACnet ATEC 550-445 (All versions), BACnet ATEC 550-446 (All versions). Affected devices improperly handle specific incoming BACnet MSTP messages. This could allow an attacker residing in the same BACnet network to send a specially crafted MSTP message that results in a denial of service condition of the targeted device. A power cycle is required to restore the device's normal operation.

The advisory is shared for download at cert-portal.siemens.com. This vulnerability was named CVE-2025-40556 since 04/16/2025. The exploitation appears to be easy. Access to the local network is required for this attack to succeed. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 05/13/2025).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

Siemens

Name

License

commercial

Website

Vendor: https://www.siemens.com/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔍
CNA CVSS-BT Score: 🔍
CNA Vector: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.5

VulDB Base Score: 6.5
VulDB Temp Score: 6.5
VulDB Vector: 🔍
VulDB Reliability: 🔍

CNA Base Score: 6.5
CNA Vector (siemens): 🔍

CVSSv2info

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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Denial of service
CWE: CWE-404
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Partially

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔍

Timelineinfo

04/16/2025 🔍
05/13/2025 +27 days 🔍
05/13/2025 +0 days 🔍
05/13/2025 +0 days 🔍

Sourcesinfo

Vendor: siemens.com

Advisory: ssa-828116
Status: Confirmed

CVE: CVE-2025-40556 (🔍)
GCVE (CVE): GCVE-0-2025-40556
GCVE (VulDB): GCVE-100-308608

Entryinfo

Created: 05/13/2025 12:48
Changes: 05/13/2025 12:48 (74)
Complete: 🔍
Cache ID: 216::103