CVE-2026-33550 addresses a security vulnerability in Alinto's SOGo collaboration suite prior to version 5.12.5, related to the implementation of OTP-based multi-factor authentication. The vulnerability arises because the system does not renew the OTP secret when a user disables and then re-enables OTP MFA, meaning the same OTP secret remains active. Additionally, the OTP length is limited to 12 digits, which is significantly shorter than the recommended 20-digit length for robust security. This combination weakens the second factor's effectiveness, potentially allowing attackers to guess or replay OTPs more easily. The vulnerability is classified under CWE-308, indicating the use of single-factor authentication or weak multi-factor authentication mechanisms. The CVSS v3.1 base score is 2.0, reflecting low severity due to the requirement of high privileges (PR:H), user interaction (UI:R), and high attack complexity (AC:H). The vulnerability does not impact confidentiality but can lead to integrity loss if an attacker successfully bypasses MFA. No known exploits have been reported, and no patches are explicitly linked, but upgrading to version 5.12.5 or later is advised. This vulnerability highlights the importance of proper OTP lifecycle management and adherence to recommended OTP length standards to maintain strong authentication security.

The primary impact of this vulnerability is a reduction in the security strength of the multi-factor authentication mechanism in SOGo, potentially allowing attackers with sufficient privileges and user interaction to bypass or weaken the second authentication factor. This could lead to unauthorized access to user accounts, compromising the integrity of email and collaboration data. While confidentiality and availability are not directly affected, unauthorized account access can facilitate further attacks such as phishing, data manipulation, or lateral movement within an organization. The low CVSS score and lack of known exploits suggest limited immediate risk, but organizations relying on SOGo for secure communications could face increased risk if attackers exploit this weakness in OTP management. The impact is more pronounced in environments where SOGo is a critical communication platform and where MFA is relied upon heavily for securing user access.

Organizations should upgrade Alinto SOGo to version 5.12.5 or later, where this vulnerability is addressed. Administrators must ensure that OTP secrets are properly renewed whenever users disable and re-enable MFA to prevent reuse of old OTP secrets. Increasing the OTP length to at least the recommended 20 digits will significantly enhance the security of the second factor. Additionally, organizations should audit their MFA configurations to verify compliance with best practices, including enforcing strong OTP generation parameters and monitoring for unusual authentication patterns. User education on the importance of MFA and cautious handling of authentication settings can further reduce risk. Implementing additional layers of security such as device-based authentication or hardware tokens may also help mitigate risks associated with weak OTP implementations.