CVE-2021-21090 is a path traversal vulnerability (CWE-22) found in Adobe InCopy version 16.0 and earlier. The vulnerability arises due to improper limitation of a pathname when the software parses a crafted file. An attacker can exploit this flaw by crafting a malicious file that, when opened by a user in Adobe InCopy, allows the attacker to traverse directories outside the intended restricted directory. This can lead to remote code execution (RCE) in the context of the current user. The attack requires no authentication but does require user interaction, specifically that the victim opens the malicious file. The vulnerability leverages the path traversal to potentially overwrite or execute arbitrary files, compromising the confidentiality, integrity, and availability of the affected system. No known exploits are currently reported in the wild, and no official patches or fixes were linked in the provided information. The vulnerability was publicly disclosed on June 28, 2021, and has been enriched by CISA, indicating recognition by US cybersecurity authorities. The lack of a CVSS score necessitates an independent severity assessment based on the technical details and impact potential.

For European organizations, the impact of CVE-2021-21090 can be significant, especially for those relying on Adobe InCopy for editorial, publishing, and content creation workflows. Successful exploitation could lead to unauthorized code execution, allowing attackers to install malware, steal sensitive data, or disrupt operations. Given that Adobe InCopy is widely used in media, publishing houses, and marketing departments, a compromise could lead to intellectual property theft, reputational damage, and operational downtime. The requirement for user interaction (opening a malicious file) means that phishing or social engineering campaigns could be vectors for exploitation, increasing risk in organizations with less mature cybersecurity awareness. Additionally, the vulnerability affects the confidentiality and integrity of data processed or stored by InCopy, and could also impact availability if exploited to deploy ransomware or destructive payloads. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits over time. Organizations with high-value content or sensitive editorial workflows are particularly at risk.

1. Immediate mitigation should focus on user awareness and training to avoid opening files from untrusted or unknown sources, especially unsolicited attachments or downloads. 2. Implement email filtering and sandboxing to detect and block potentially malicious files targeting Adobe InCopy users. 3. Restrict Adobe InCopy usage to trusted networks and environments, and consider application whitelisting to prevent unauthorized execution of unknown files. 4. Monitor for unusual file access or execution patterns related to InCopy processes using endpoint detection and response (EDR) tools. 5. Since no official patches are linked, organizations should check Adobe’s official security advisories regularly for updates or patches addressing this vulnerability and apply them promptly once available. 6. Employ file integrity monitoring on directories used by InCopy to detect unauthorized changes that could indicate exploitation attempts. 7. Consider isolating or sandboxing the InCopy application environment to limit the impact of potential exploitation. 8. Review and tighten file permissions and user privileges to minimize the scope of code execution under the current user context.