CVE-2026-21340 is an out-of-bounds read vulnerability classified under CWE-125 affecting Adobe Substance3D - Designer versions 15.1.0 and earlier. The vulnerability arises when the software improperly handles memory bounds during file processing, allowing an attacker to read memory locations outside the intended buffer. This can lead to the exposure of sensitive information stored in memory, such as internal application data or potentially sensitive user information. Exploitation requires a victim to open a specially crafted malicious file, making user interaction mandatory. The vulnerability does not allow modification of data or code execution, limiting its impact to information disclosure. The CVSS v3.1 base score is 5.5, reflecting a medium severity with attack vector local (AV:L), low attack complexity (AC:L), no privileges required (PR:N), user interaction required (UI:R), unchanged scope (S:U), and impact limited to availability (A:H) but no confidentiality or integrity impact. No patches or exploits are currently publicly available, but the vulnerability is officially published and reserved since December 2025. This vulnerability primarily threatens confidentiality through memory exposure, but the lack of known exploits and the requirement for user interaction reduce its immediate risk.

For European organizations, the primary impact is the potential disclosure of sensitive information residing in memory when a malicious file is opened in Adobe Substance3D - Designer. This could include proprietary design data or internal application state, which may be valuable to industrial espionage or competitive intelligence. The requirement for user interaction and the absence of privilege escalation or remote exploitation limit the risk to targeted attacks rather than widespread automated compromise. However, organizations in creative industries, digital content creation, and media production that rely on Adobe Substance3D - Designer may face confidentiality risks if attackers craft malicious files and successfully convince users to open them. The impact on availability is minimal, and integrity is not affected. Given the medium severity, the threat is moderate but should not be ignored, especially in environments with high-value intellectual property.

Organizations should educate users about the risks of opening files from untrusted or unknown sources, particularly in Adobe Substance3D - Designer. Implement strict file validation and sandboxing where possible to limit the impact of malicious files. Monitor and restrict the use of Adobe Substance3D - Designer to trusted personnel and environments. Regularly check for updates or patches from Adobe addressing this vulnerability and apply them promptly once available. Employ endpoint detection and response (EDR) solutions to detect unusual application behavior that might indicate exploitation attempts. Consider network segmentation to isolate systems running Substance3D - Designer from critical infrastructure. Finally, maintain robust backup and incident response plans to quickly recover from any potential compromise.