CVE-2021-27102 is a high-severity vulnerability affecting Accellion File Transfer Appliance (FTA) versions 9_12_411 and earlier. This vulnerability allows an attacker with local access and low privileges to execute arbitrary operating system commands via a local web service call. The vulnerability is classified under CWE-78, which corresponds to OS Command Injection, indicating that unsanitized input is passed to a system shell or command interpreter, enabling command execution. The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability. The attack vector is local (AV:L), requiring low attack complexity (AC:L) and low privileges (PR:L), but no user interaction (UI:N). The scope is unchanged (S:U), meaning the vulnerability affects resources under the same security authority. Exploitation could lead to full system compromise, data theft, or disruption of services. The fixed version is FTA_9_12_416 and later, indicating that patching is the primary remediation. No known exploits in the wild have been reported, but the potential for exploitation exists given the nature of the vulnerability and the criticality of the affected system. Accellion FTA is used for secure file transfer, often in enterprise and government environments, making this vulnerability particularly sensitive.

For European organizations, the impact of CVE-2021-27102 can be significant. Accellion FTA is commonly used for secure file transfers involving sensitive or regulated data, including personal data protected under GDPR. Exploitation could lead to unauthorized access to confidential files, data exfiltration, or disruption of critical file transfer operations. This could result in data breaches, regulatory penalties, reputational damage, and operational downtime. Given the high confidentiality, integrity, and availability impact, organizations relying on Accellion FTA for inter-organizational or cross-border data exchange are at risk. The requirement for local access and low privileges means that insider threats or attackers who have gained limited access could leverage this vulnerability to escalate privileges and compromise the system further. The absence of known exploits in the wild does not eliminate the risk, as threat actors may develop exploits targeting this vulnerability, especially in sectors with high-value data such as finance, healthcare, and government.

European organizations should immediately verify their Accellion FTA version and upgrade to version 9_12_416 or later to remediate this vulnerability. Beyond patching, organizations should implement strict access controls to limit local access to the FTA system, ensuring only trusted administrators have such privileges. Employ network segmentation to isolate the FTA appliance from less secure network zones, reducing the risk of lateral movement. Monitor system logs and web service calls for unusual activity indicative of command injection attempts. Implement application whitelisting and endpoint detection and response (EDR) solutions to detect and prevent unauthorized command execution. Conduct regular security audits and penetration testing focused on the FTA environment. Additionally, review and enforce strong authentication mechanisms and consider multi-factor authentication for administrative access. Finally, ensure incident response plans include scenarios for exploitation of this vulnerability to enable rapid containment and remediation.