CVE-2025-41077 is an authorization bypass vulnerability identified in Viafirma Inbox version 4.5.13, categorized under CWE-639 (Authorization Bypass Through User-Controlled Key). The vulnerability is an Insecure Direct Object Reference (IDOR) that allows any authenticated user, regardless of their assigned privileges, to list all users within the application and access or modify their data. Specifically, attackers can alter users' email addresses, which can then be leveraged to exploit the password recovery functionality. By changing the email address associated with a target user account, an attacker can trigger password reset processes and gain unauthorized access by impersonating that user, including high-privilege administrative accounts. The vulnerability does not require elevated privileges or user interaction, and the attack vector is network-based with low complexity. The CVSS v4.0 score is 8.6 (high), reflecting the critical impact on confidentiality and integrity, as well as the ease of exploitation. No patches or public exploits are currently available, but the flaw poses a significant risk to organizations relying on this product for secure communications and document management. The root cause is inadequate authorization checks on user-controlled keys, allowing unauthorized enumeration and modification of user data.

For European organizations, the impact of CVE-2025-41077 can be substantial. Unauthorized access to user accounts, especially administrative ones, can lead to full compromise of the Viafirma Inbox environment, exposing sensitive communications and documents. This can result in data breaches, loss of confidentiality, and potential regulatory non-compliance under GDPR due to unauthorized access to personal data. Attackers could manipulate email addresses to intercept password resets, facilitating lateral movement and privilege escalation within the affected environment. The ability to impersonate users undermines trust in the platform and could disrupt business operations relying on secure document workflows. Given the widespread use of Viafirma Inbox in sectors such as finance, government, and legal services across Europe, the risk of espionage, fraud, and operational disruption is heightened. The lack of known exploits in the wild suggests a window for proactive mitigation, but the vulnerability's characteristics make it a prime target for attackers once weaponized.

Organizations should immediately verify if they are running Viafirma Inbox version 4.5.13 and prioritize upgrading to a patched version once available. In the absence of an official patch, implement strict access controls to limit authenticated user capabilities and monitor for unusual user enumeration or modification activities. Disable or restrict the password recovery functionality temporarily to prevent exploitation via email address changes. Employ application-layer firewalls or WAFs to detect and block suspicious requests targeting user enumeration or modification endpoints. Conduct thorough audits of user account changes and password reset logs to identify potential abuse. Additionally, enforce multi-factor authentication (MFA) for all users, especially administrators, to mitigate the risk of account takeover. Engage with Viafirma support for guidance and monitor security advisories for updates. Finally, educate users about phishing and social engineering risks that could compound this vulnerability.