CVE-2021-27103 is a critical Server-Side Request Forgery (SSRF) vulnerability affecting Accellion File Transfer Appliance (FTA) versions 9_12_411 and earlier. SSRF vulnerabilities allow an attacker to induce the server-side application to make HTTP requests to arbitrary domains or internal systems that the attacker would not normally have access to. In this case, the vulnerability is triggered via a crafted POST request to the endpoint wmProgressstat.html. Exploiting this flaw could allow an unauthenticated attacker to send arbitrary requests from the vulnerable Accellion FTA server, potentially accessing internal resources, sensitive data, or services that are otherwise protected behind firewalls or network segmentation. The vulnerability has a CVSS v3.1 base score of 9.8, indicating a critical severity level, with attack vector being network-based, no privileges or user interaction required, and impacts on confidentiality, integrity, and availability. The vulnerability is classified under CWE-918 (Server-Side Request Forgery). The fixed version is FTA_9_12_416 and later, so upgrading to these versions or beyond is essential. No known exploits in the wild have been reported at the time of publication, but the high severity and ease of exploitation make this a significant risk for organizations using affected Accellion FTA versions. Accellion FTA is a secure file transfer appliance used by enterprises and government agencies to exchange sensitive files, often containing confidential or regulated data, making the impact of this vulnerability potentially severe if exploited.

For European organizations, the impact of this SSRF vulnerability in Accellion FTA can be substantial. Many European enterprises and public sector entities rely on secure file transfer solutions like Accellion FTA to handle sensitive personal data, intellectual property, and regulated information under frameworks such as GDPR. Exploitation could lead to unauthorized internal network access, data exfiltration, and potential lateral movement within the network. This could result in breaches of personal data, leading to regulatory fines, reputational damage, and operational disruption. Given the criticality of the vulnerability and the fact that it requires no authentication or user interaction, attackers could remotely exploit vulnerable systems from anywhere. The confidentiality, integrity, and availability of data and services could be compromised, affecting business continuity and compliance obligations. Additionally, internal systems that are normally shielded from external access could be exposed, increasing the risk of further compromise or espionage. The lack of known exploits in the wild does not reduce the urgency, as the vulnerability’s characteristics make it a prime target for attackers seeking to gain footholds in enterprise environments.

European organizations using Accellion FTA should immediately upgrade to version 9_12_416 or later to remediate this SSRF vulnerability. If immediate upgrade is not feasible, organizations should implement network-level controls such as restricting outbound HTTP/HTTPS requests from the Accellion FTA appliance to only trusted destinations, using firewall rules or proxy filtering to block unauthorized external or internal requests. Monitoring and logging of all requests made by the FTA appliance should be enhanced to detect anomalous or suspicious activity indicative of SSRF exploitation attempts. Additionally, organizations should conduct thorough network segmentation to limit the appliance’s access to sensitive internal systems. Regular vulnerability scanning and penetration testing focused on SSRF and related web application vulnerabilities should be performed. Incident response plans should be updated to include detection and containment strategies for SSRF exploitation. Finally, organizations should review and audit all file transfer workflows and data access policies to minimize exposure of sensitive data through the appliance.