CVE-2000-0111 in Rightfax
Summary
by MITRE
The RightFax web client uses predictable session numbers, which allows remote attackers to hijack user sessions.
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Analysis
by VulDB Data Team • 04/20/2026
The vulnerability identified as CVE-2000-0111 resides within the RightFax web client implementation where session management lacks sufficient randomness in session identifier generation. This weakness creates a predictable session number pattern that adversaries can exploit to conduct session hijacking attacks against authenticated users. The flaw stems from inadequate entropy in the session token creation process, allowing malicious actors to guess valid session identifiers and assume legitimate user identities within the fax server environment.
This vulnerability directly maps to CWE-330 Use of Insufficiently Random Values, which specifically addresses the use of weak random number generators or predictable sequences in security-critical contexts. The predictable nature of session identifiers violates fundamental security principles for session management and authentication. From an operational perspective, this vulnerability represents a critical weakness in the web application's authentication framework, as it eliminates the primary defense mechanism protecting user sessions from unauthorized access.
The attack surface for this vulnerability extends across all web-based interactions with the RightFax system where session persistence is maintained. Remote attackers can leverage this weakness without requiring local system access or privileged credentials, making it particularly dangerous in networked environments. The session hijacking capability allows attackers to perform actions with the privileges of legitimate users, potentially enabling unauthorized fax transmission, access to sensitive documents, or modification of system configurations. This vulnerability particularly impacts organizations relying on web-based fax services where user authentication is critical for maintaining confidentiality and integrity of document workflows.
Mitigation strategies for CVE-2000-0111 should focus on implementing robust session management practices including the use of cryptographically secure random number generators for session identifier creation. Organizations should ensure that session tokens contain sufficient entropy and are generated using proper cryptographic methods. Network segmentation and additional authentication layers such as multi-factor authentication can provide compensating controls while permanent fixes are implemented. The implementation of session timeout mechanisms and automatic session invalidation upon logout or inactivity further reduces the window of opportunity for exploitation. This vulnerability also highlights the importance of following secure coding practices and conducting regular security assessments of web applications to identify and remediate predictable sequence generation issues. Organizations should consider implementing web application firewalls and intrusion detection systems to monitor for suspicious session-related activities that may indicate exploitation attempts.