CVE-2026-21281 is a heap-based buffer overflow vulnerability (CWE-122) found in Adobe InCopy versions 21.0, 19.5.5, and earlier. The vulnerability arises from improper handling of heap memory when processing certain file inputs, allowing an attacker to overwrite memory buffers beyond their allocated size. This memory corruption can lead to arbitrary code execution within the context of the current user. Exploitation requires the victim to open a maliciously crafted InCopy file, making user interaction mandatory. The vulnerability does not require elevated privileges or prior authentication, increasing its risk profile. The CVSS v3.1 score of 7.8 reflects high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges required. Although no active exploits have been reported in the wild, the potential for attackers to leverage this flaw for remote code execution and lateral movement within networks is significant. Adobe has not yet released a patch, so organizations must rely on interim mitigations. This vulnerability is particularly critical for environments where Adobe InCopy is used extensively, such as media, publishing, and creative agencies, as compromise could lead to data theft, system takeover, or disruption of operations.

For European organizations, the impact of CVE-2026-21281 can be severe. Successful exploitation could lead to arbitrary code execution, allowing attackers to steal sensitive data, deploy malware, or disrupt business processes. Given Adobe InCopy's prevalence in creative and publishing industries, organizations in these sectors face heightened risk of intellectual property theft and operational downtime. The vulnerability affects confidentiality by exposing potentially sensitive documents, integrity by enabling unauthorized code execution, and availability by possibly causing application or system crashes. The requirement for user interaction means phishing or social engineering campaigns could be used to deliver malicious files, increasing the attack surface. Additionally, compromised endpoints could serve as footholds for broader network intrusion, impacting supply chains and partners. European data protection regulations such as GDPR heighten the consequences of breaches, including financial penalties and reputational damage. Therefore, the threat is particularly relevant to organizations handling large volumes of creative content or sensitive client information.

Until Adobe releases an official patch, European organizations should implement several targeted mitigations: 1) Disable or restrict the ability to open InCopy files from untrusted or external sources, including email attachments and downloads. 2) Educate users about the risks of opening files from unknown or suspicious origins and enforce strict policies on file handling. 3) Employ endpoint protection solutions with advanced behavior-based detection to identify and block exploitation attempts involving heap corruption. 4) Use application whitelisting to limit execution of unauthorized code and scripts. 5) Disable file preview features in email clients and file explorers to prevent automatic triggering of the vulnerability. 6) Monitor network and endpoint logs for unusual activity indicative of exploitation attempts. 7) Segment networks to contain potential breaches and limit lateral movement. 8) Prepare for rapid deployment of patches once Adobe releases updates by maintaining an up-to-date asset inventory of affected InCopy versions. These measures go beyond generic advice by focusing on controlling file sources, user behavior, and detection capabilities specific to this vulnerability's exploitation vector.