CVE-2026-21343 is an out-of-bounds read vulnerability classified under CWE-125 affecting Adobe Substance3D - Stager versions 3.1.6 and earlier. The flaw arises during the parsing of crafted files, where the software reads memory beyond the allocated buffer, potentially exposing sensitive data or corrupting memory. This memory corruption can be leveraged by attackers to execute arbitrary code within the context of the current user. The attack vector requires local access and user interaction, meaning the victim must open a maliciously crafted file, typically delivered via phishing or social engineering. The vulnerability has a CVSS 3.1 base score of 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges required. Although no exploits are currently known in the wild, the potential for code execution makes this a significant risk, especially in environments where Adobe Substance3D - Stager is used for 3D content creation and design workflows. The lack of an available patch at the time of publication necessitates immediate mitigation strategies to reduce exposure.

For European organizations, this vulnerability poses a substantial risk to the confidentiality and integrity of sensitive design and creative assets, as well as the availability of critical design tools. Exploitation could lead to unauthorized code execution, enabling attackers to deploy malware, steal intellectual property, or disrupt operations. Industries relying heavily on digital content creation, such as media, entertainment, automotive design, and manufacturing, could face operational disruptions and data breaches. Given the requirement for user interaction, targeted phishing campaigns could be an effective attack vector, increasing the risk for organizations with less mature security awareness programs. The potential for lateral movement within networks exists if attackers gain a foothold via compromised user accounts. Additionally, the high CVSS score indicates that the vulnerability could be leveraged to cause significant damage if exploited.

Organizations should immediately implement strict controls around the handling of files associated with Adobe Substance3D - Stager, including disabling automatic file opening and enforcing strict email attachment policies. User training to recognize and avoid opening suspicious or unexpected files is critical. Network segmentation should be employed to limit the spread of any compromise originating from a vulnerable host. Monitoring for unusual process behavior or memory access patterns related to Substance3D - Stager can help detect exploitation attempts. Until an official patch is released, consider restricting Substance3D - Stager usage to trusted files and users only. Employ application whitelisting and endpoint detection and response (EDR) solutions to identify and block exploitation attempts. Regularly check Adobe’s security advisories for updates and apply patches promptly once available.