CVE-2026-21305 is an out-of-bounds write vulnerability (CWE-787) identified in Adobe Substance3D - Painter, a widely used 3D texturing and painting software. The vulnerability exists in versions 11.0.3 and earlier and allows an attacker to write data outside the bounds of allocated memory. This memory corruption can be leveraged to execute arbitrary code within the context of the current user. The attack vector requires user interaction, specifically the victim opening a maliciously crafted file designed to trigger the vulnerability. The CVSS v3.1 base score is 7.8, indicating high 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 high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). Although no public exploits are known at this time, the potential for arbitrary code execution makes this a significant risk, especially in environments where users frequently exchange or open files from untrusted sources. The vulnerability could allow attackers to compromise systems, steal sensitive data, or disrupt operations by executing malicious payloads. Adobe has not yet released patches, so users must rely on interim mitigations.

For European organizations, the impact of this vulnerability can be substantial, particularly for those in digital content creation, gaming, animation, and industrial design sectors that rely on Adobe Substance3D - Painter. Successful exploitation could lead to unauthorized code execution, resulting in data breaches, intellectual property theft, or disruption of critical workflows. Since the vulnerability requires user interaction, phishing or social engineering campaigns could be used to deliver malicious files. The compromise of workstations could serve as a foothold for lateral movement within corporate networks, potentially affecting broader IT infrastructure. Confidentiality is at high risk due to potential data exfiltration, integrity is compromised by unauthorized code execution, and availability could be impacted if systems are destabilized or malware is deployed. The lack of known exploits currently reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits rapidly after public disclosure.

1. Monitor Adobe’s official channels for patch releases and apply updates promptly once available. 2. Until patches are released, restrict the opening of files from untrusted or unknown sources within Substance3D - Painter. 3. Implement strict email filtering and user awareness training to reduce the risk of phishing attacks delivering malicious files. 4. Use application whitelisting to limit execution of unauthorized code on endpoints running Substance3D - Painter. 5. Employ endpoint detection and response (EDR) solutions to detect anomalous behavior indicative of exploitation attempts. 6. Enforce the principle of least privilege for users running Substance3D - Painter to minimize the impact of potential code execution. 7. Regularly back up critical data and ensure backups are isolated from the main network to enable recovery from potential ransomware or destructive attacks. 8. Consider sandboxing or isolating the application environment to contain potential exploits.