CVE-2026-23720: Siemens Simcenter Femap RCE Vulnerability

CVE-2026-23720 Overview

A critical out-of-bounds read vulnerability has been identified in Siemens Simcenter Femap and Simcenter Nastran engineering simulation software. The vulnerability occurs during the parsing of specially crafted NDB files, which could allow an attacker to execute arbitrary code in the context of the current process. This presents a significant risk to organizations utilizing these simulation tools in engineering and manufacturing environments.

Critical Impact

Successful exploitation of this vulnerability could allow attackers to achieve code execution by convincing users to open maliciously crafted NDB files, potentially compromising sensitive engineering data and intellectual property.

Affected Products

• Siemens Simcenter Femap (All versions < V2512)
• Siemens Simcenter Nastran (All versions < V2512)

Discovery Timeline

• 2026-02-10 - CVE-2026-23720 published to NVD
• 2026-02-11 - Last updated in NVD database

Technical Details for CVE-2026-23720

Vulnerability Analysis

This vulnerability is classified as CWE-125 (Out-of-Bounds Read), a memory corruption issue that occurs when the application reads data from a memory location outside the bounds of the intended buffer. In the context of Simcenter Femap and Nastran, the flaw manifests during the parsing of NDB (Nastran Database) files.

When processing a maliciously crafted NDB file, the affected applications fail to properly validate input boundaries before reading file data into memory. This allows an attacker to construct a file that triggers the application to read beyond allocated buffer boundaries, potentially exposing sensitive memory contents or causing application instability.

The attack requires local access and user interaction, meaning a victim must be convinced to open the malicious NDB file. However, given the collaborative nature of engineering workflows where file sharing is common, this attack vector remains viable in targeted scenarios.

Root Cause

The root cause of CVE-2026-23720 lies in insufficient boundary validation within the NDB file parsing routines. The application does not adequately verify that data offsets and lengths specified within the NDB file structure remain within the bounds of allocated memory buffers. When parsing malformed or specially crafted NDB files, the application trusts file-supplied values without proper sanitization, leading to memory reads beyond the intended boundaries.

Attack Vector

The attack vector for this vulnerability is local, requiring user interaction to exploit. An attacker would need to craft a malicious NDB file containing manipulated data structures designed to trigger the out-of-bounds read condition. The attack scenario typically involves:

1. The attacker creates a specially crafted NDB file with malformed data offsets or size fields
2. The attacker delivers the malicious file to the target through email, file sharing, or other delivery mechanisms
3. The victim opens the NDB file using Simcenter Femap or Simcenter Nastran
4. The vulnerable parsing routine reads beyond buffer boundaries
5. Code execution occurs in the context of the current process

The vulnerability does not require authentication or elevated privileges, making social engineering the primary delivery mechanism for exploitation.

Detection Methods for CVE-2026-23720

Indicators of Compromise

• Unexpected crashes or instability in Simcenter Femap or Simcenter Nastran applications
• Unusual NDB files received from external or untrusted sources
• Application event logs showing memory access violations during file parsing operations
• Suspicious file access patterns involving NDB files from non-standard directories

Detection Strategies

• Implement file integrity monitoring for NDB files in engineering directories
• Deploy endpoint detection and response (EDR) solutions to monitor for anomalous memory access patterns in Simcenter applications
• Configure application whitelisting to control which files can be opened by Simcenter products
• Enable verbose logging for Simcenter applications to capture file parsing errors

Monitoring Recommendations

• Monitor for unusual process behavior from femap.exe and Nastran-related executables
• Track file system activity involving NDB files, especially those originating from external sources
• Implement network monitoring to detect suspicious file transfers of NDB files
• Enable Windows Event logging for application crashes and memory access violations

How to Mitigate CVE-2026-23720

Immediate Actions Required

• Upgrade Simcenter Femap and Simcenter Nastran to version V2512 or later
• Implement strict file source validation policies for NDB files
• Train users to avoid opening NDB files from untrusted or unknown sources
• Deploy application sandboxing where feasible to limit the impact of exploitation

Patch Information

Siemens has released version V2512 of both Simcenter Femap and Simcenter Nastran to address this vulnerability. Organizations should prioritize upgrading to the patched versions immediately. Detailed patch information and download links are available in the Siemens Security Advisory SSA-965753.

Workarounds

• Restrict NDB file handling to trusted sources only until patches can be applied
• Implement network segmentation to isolate engineering workstations
• Use virtual machines or sandboxed environments for opening NDB files from external parties
• Apply principle of least privilege to limit the impact of potential code execution

# Configuration example
# Implement file extension blocking at the email gateway for untrusted NDB files
# Example Siemens Simcenter directory protection via Windows AppLocker
New-AppLockerPolicy -RuleType Path -FilePathCondition "%USERPROFILE%\Downloads\*.ndb" -User Everyone -Action Deny