CVE-2022-39018 is a high-severity vulnerability affecting M-Files Hubshare versions prior to 3.3.11.3, specifically version 3.3.1.6 as identified. The vulnerability arises from broken access controls related to PDFtron data handling within the Hubshare platform. Due to improper authorization checks, unauthenticated attackers can access restricted PDF files by leveraging a known URL pattern. This exposure constitutes a CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) vulnerability, compounded by weaknesses categorized under CWE-639 (Authorization Bypass Through User-Controlled Key) and CWE-287 (Improper Authentication). The CVSS 3.1 base score of 8.2 reflects the significant confidentiality impact (high), with limited integrity and availability impacts (low). The attack vector is network-based (AV:N), requiring low attack complexity (AC:L), but does require privileges (PR:L) and user interaction (UI:R), with a scope change (S:C) indicating that exploitation affects resources beyond the initially vulnerable component. The vulnerability allows unauthorized disclosure of sensitive PDF documents stored or managed via the Hubshare platform, potentially exposing confidential business, legal, or personal data. No known public exploits have been reported to date, but the vulnerability’s nature and ease of exploitation make it a critical concern for organizations relying on affected versions of M-Files Hubshare. The lack of available patches at the time of reporting necessitates immediate mitigation efforts to prevent unauthorized data access.

For European organizations, the exposure of sensitive PDF documents through this vulnerability can lead to significant data breaches involving intellectual property, personal data protected under GDPR, or confidential contractual information. The unauthorized access to restricted files undermines data confidentiality and may result in regulatory penalties, reputational damage, and loss of customer trust. Given the scope change indicated by the CVSS vector, the breach could extend beyond a single user or system, potentially compromising multiple departments or clients. Organizations in sectors such as legal, finance, healthcare, and government, which often use document management solutions like M-Files Hubshare, are particularly at risk. The vulnerability could also facilitate further attacks by providing threat actors with sensitive information useful for social engineering or targeted intrusions. The requirement for user interaction and low privilege suggests that insider threats or phishing campaigns could be leveraged to exploit this vulnerability, increasing the attack surface. Overall, the impact on confidentiality is critical, while integrity and availability impacts are limited but non-negligible.

Upgrade M-Files Hubshare to version 3.3.11.3 or later as soon as the patch becomes available to ensure proper access control enforcement. Implement strict network segmentation and access controls to limit exposure of Hubshare services to trusted internal networks only, reducing the attack surface from external unauthenticated actors. Monitor and audit access logs for unusual or unauthorized access patterns to PDF files, focusing on access via direct URLs or unexpected sources. Enforce multi-factor authentication (MFA) for all users accessing Hubshare to mitigate risks from low privilege exploitation and user interaction requirements. Conduct regular security assessments and penetration testing focused on document management systems to identify and remediate similar authorization weaknesses. Educate users about phishing and social engineering risks that could facilitate exploitation requiring user interaction. If immediate patching is not feasible, consider temporarily disabling or restricting access to PDFtron-related features or sensitive document repositories within Hubshare.