CVE-1999-1340 describes a buffer overflow vulnerability in the 'faxalter' utility of HylaFAX version 4.0.2. HylaFAX is an open-source fax server system used to send and receive faxes over telephone lines. The vulnerability arises from improper handling of the '-m' command line argument in the 'faxalter' program, where a local user can supply an excessively long string. This causes a buffer overflow, allowing the attacker to overwrite adjacent memory regions. Because 'faxalter' runs with elevated privileges, exploiting this overflow can lead to privilege escalation, enabling a local attacker to gain root or administrative access on the affected system. The vulnerability requires local access and does not need user interaction beyond executing the command with the crafted argument. The CVSS score of 7.2 (high severity) reflects the critical impact on confidentiality, integrity, and availability, given that the attacker can fully compromise the system. No patch is available for this vulnerability, and no known exploits have been reported in the wild. However, the age of the vulnerability (published in 1999) suggests that affected systems are likely legacy or unmaintained. The vulnerability specifically affects HylaFAX version 4.0.2, so only systems running this exact version are at risk.

For European organizations, the impact of this vulnerability depends on the continued use of HylaFAX 4.0.2 in their infrastructure. If legacy fax servers running this version are still operational, an attacker with local access could escalate privileges and gain full control over the fax server machine. This could lead to unauthorized access to sensitive fax communications, disruption of fax services, and potential lateral movement within the network. Given the critical nature of the vulnerability, confidentiality, integrity, and availability of fax-related data and systems could be severely compromised. Organizations in sectors relying on fax communications for sensitive data exchange—such as healthcare, legal, and government agencies—may face significant risks. Additionally, compromised fax servers could be used as footholds for further attacks against internal networks. However, the requirement for local access limits the attack surface, reducing the likelihood of remote exploitation unless combined with other vulnerabilities or insider threats.

Since no official patch is available for this vulnerability, European organizations should consider the following specific mitigation steps: 1) Immediately identify and inventory any systems running HylaFAX version 4.0.2. 2) Decommission or upgrade these systems to a more recent, supported version of HylaFAX or replace fax functionality with modern, secure alternatives. 3) Restrict local access to fax server machines strictly to trusted administrators, employing strong access controls and monitoring. 4) Implement host-based intrusion detection systems (HIDS) to detect anomalous usage of the 'faxalter' utility or attempts to exploit command line arguments. 5) Employ application whitelisting to prevent unauthorized execution of 'faxalter' or limit its usage context. 6) Conduct regular security audits and network segmentation to isolate fax servers from critical infrastructure. 7) Educate system administrators about the risks of legacy software and the importance of timely upgrades. These targeted mitigations go beyond generic advice by focusing on legacy system identification, access restriction, and monitoring specific to the vulnerable utility.