CVE-2025-40762 Overview
CVE-2025-40762 is an out-of-bounds write vulnerability in Siemens Simcenter Femap, a finite element modeling application used in engineering simulation workflows. The flaw exists in the STP file parser and is triggered when a user opens a specially crafted STEP (.stp) file. Successful exploitation allows an attacker to execute arbitrary code in the context of the current process. The issue affects Simcenter Femap V2406 versions prior to V2406.0003 and V2412 versions prior to V2412.0002. The vulnerability was reported through the Zero Day Initiative under identifier ZDI-CAN-26692 and is tracked by Siemens under advisory SSA-674084.
Critical Impact
An attacker can achieve arbitrary code execution on engineering workstations by convincing a user to open a malicious STP file, exposing CAD/CAE intellectual property and providing a foothold in OT-adjacent environments.
Affected Products
- Siemens Simcenter Femap V2406 (all versions prior to V2406.0003)
- Siemens Simcenter Femap V2412 (all versions prior to V2412.0002)
- File format affected: STEP (.stp) CAD exchange files
Discovery Timeline
- 2025-08-12 - CVE-2025-40762 published to the National Vulnerability Database
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-40762
Vulnerability Analysis
The vulnerability is an out-of-bounds write classified under [CWE-787]. It resides in the routines Simcenter Femap uses to parse STEP (.stp) files, an ISO 10303 format commonly exchanged between CAD and CAE tools. When the parser processes attacker-controlled fields in a malformed STP file, it writes data beyond the bounds of an allocated buffer. Because the write occurs in the same process that loads the file, an attacker can corrupt adjacent memory structures and steer execution into attacker-controlled code. Exploitation requires user interaction: the victim must open or import the crafted file. No network access or elevated privileges are required to deliver the payload.
Root Cause
The root cause is missing or insufficient bounds validation while deserializing entity records inside the STP parser. STEP files describe geometric entities, lengths, and references as ASCII tokens, and parsers must validate every length and index before copying data into fixed-size buffers. In the affected Femap builds, at least one code path trusts an attacker-influenced size or offset, leading to a write past the end of the destination buffer.
Attack Vector
The attack vector is local and requires user interaction. A typical scenario involves an attacker distributing a crafted .stp file via email, a shared engineering repository, a supplier portal, or a removable drive. When the targeted engineer opens the file in Simcenter Femap, the parser triggers the out-of-bounds write and the attacker gains code execution under the user's account. From that position, the attacker can pivot to harvest design data, deploy implants, or move laterally into connected engineering networks. Technical exploitation details are described in the Siemens Security Advisory SSA-674084.
Detection Methods for CVE-2025-40762
Indicators of Compromise
- Unexpected child processes spawned by femap.exe shortly after a .stp file is opened, particularly shells, scripting hosts, or rundll32.exe.
- Crash artifacts (Windows Error Reporting entries, .dmp files) referencing the Femap process and STP parsing modules.
- Inbound .stp files from unverified suppliers or external email senders staged in user Downloads or shared engineering folders.
Detection Strategies
- Hunt for process lineage anomalies where Simcenter Femap is the parent of network-facing or persistence-related binaries.
- Alert on Femap processes performing outbound network connections to non-corporate destinations, which is uncommon for a modeling application.
- Inspect .stp files at the email and web gateway for malformed STEP records and oversized entity definitions.
Monitoring Recommendations
- Enable command-line and module load logging on engineering workstations and forward telemetry to a centralized analytics platform.
- Track file-open events for Simcenter Femap and correlate with subsequent process, file, and network activity for at least 24 hours.
- Review endpoint protection telemetry for memory protection events (e.g., DEP, CFG) raised by femap.exe.
How to Mitigate CVE-2025-40762
Immediate Actions Required
- Upgrade Simcenter Femap V2406 to V2406.0003 or later, and V2412 to V2412.0002 or later, as directed in Siemens advisory SSA-674084.
- Instruct engineering users to avoid opening .stp files received from untrusted or unverified sources until patched.
- Apply application allowlisting and standard-user privileges on engineering workstations to limit blast radius if exploitation succeeds.
Patch Information
Siemens has released fixed builds: Simcenter Femap V2406.0003 and V2412.0002. Both updates remediate the STP parser out-of-bounds write tracked as CVE-2025-40762 and ZDI-CAN-26692. Download details and integrity hashes are available in the Siemens Security Advisory SSA-674084.
Workarounds
- Only process STP files originating from trusted suppliers and validated repositories.
- Open untrusted CAD exchange files inside a sandboxed or isolated virtual machine without access to engineering shares.
- Enforce email and proxy controls that quarantine .stp attachments from external senders pending review.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
