CVE-2025-21166: Out-of-Bounds Write Vulnerability in Substance3D – Designer

Overview

The CVE-2025-21166 is a newly identified cybersecurity vulnerability affecting versions 14.1 and earlier of the popular Substance3D – Designer software. This critical vulnerability can lead to an out-of-bounds write, a dangerous condition where arbitrary data can overwrite other data in memory, potentially leading to arbitrary code execution by the attacker. This issue is significant as Substance3D – Designer is widely used by creative professionals and organizations globally, raising the potential for system compromise and data leakage.

Vulnerability Summary

CVE ID: CVE-2025-21166
Severity: High (CVSS: 7.8)
Attack Vector: Local
Privileges Required: None
User Interaction: Required
Impact: Arbitrary code execution, potential system compromise, and data leakage

Affected Products

Product | Affected Versions

Substance3D – Designer | 14.1 and earlier

How the Exploit Works

The vulnerability arises from the software’s improper handling of certain file inputs, leading to an out-of-bounds write. When a user opens a specially-crafted malicious file, the application can be tricked into writing data outside of its intended memory boundaries. This can cause the application to overwrite other important data in memory, potentially leading to arbitrary code execution. This code would run in the context of the current user, making it possible for an attacker to take control of the affected system.

Conceptual Example Code

A conceptual example of how this vulnerability might be exploited could be through a malicious .sbs file (Substance3D’s native file format). The attacker crafts this file in such a way that it triggers the vulnerable code path when opened in Substance3D – Designer:

# Conceptual malicious .sbs file
{
"metadata": {...},
"content": "AAAAAAAAA...[more A's beyond expected boundary]...AAAAAA"
}

In this conceptual example, the `content` is filled with an excessive amount of “A” characters, which could trigger an out-of-bounds write if the application does not correctly handle this unexpectedly large input. Please note that this is simplified and conceptual; real-world exploits would likely need to incorporate more sophisticated techniques to achieve arbitrary code execution.

Mitigation Guidance

Substance3D users are strongly recommended to apply the vendor patch as soon as it becomes available to mitigate this vulnerability. In the meantime, using a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can provide temporary mitigation. These tools can help detect and block suspicious activities that may indicate an attempt to exploit this vulnerability. However, they are not a substitute for patching the software as they may not catch all attempts to exploit this vulnerability.