CVE-1999-1546 is a vulnerability found in the netstation.navio-com.rte 1.1.0.1 configuration script for Navio NC running on IBM AIX systems. The issue arises because the configuration script exports the /tmp directory over NFS (Network File System) with permissions that are world-readable and world-writable. This means that any remote user with network access to the NFS server can read from and write to the /tmp directory without any authentication or restrictions. The /tmp directory is typically used for temporary file storage and may contain sensitive or critical runtime data. Exposing it with such permissive access can lead to unauthorized data disclosure, data tampering, or the planting of malicious files or scripts. The vulnerability is network exploitable without authentication, and the attack complexity is low, as no special conditions are required to exploit it. The CVSS score of 5 (medium severity) reflects the partial confidentiality impact without integrity or availability impacts. There is no patch available for this vulnerability, and no known exploits have been reported in the wild. However, the misconfiguration itself poses a security risk, especially in environments where sensitive data might be temporarily stored or where attackers could leverage writable NFS shares to escalate privileges or pivot within the network.

For European organizations using IBM AIX systems with the Navio NC product version 1.1.0.1, this vulnerability could lead to unauthorized disclosure of sensitive information stored temporarily in /tmp. Attackers could also modify or plant malicious files in the writable /tmp directory, potentially enabling further attacks such as privilege escalation or lateral movement within the network. Although the vulnerability does not directly affect system integrity or availability, the exposure of temporary files could compromise confidentiality and trust in the affected systems. Organizations in sectors with stringent data protection requirements, such as finance, healthcare, and government, could face compliance risks if sensitive data is leaked. Additionally, the lack of authentication and ease of exploitation means that any attacker with network access to the affected NFS export could exploit this vulnerability, increasing the risk profile for exposed systems.

Since no official patch is available, European organizations should take immediate steps to mitigate the risk. First, review and modify the NFS export configuration to remove or restrict the export of the /tmp directory. Ideally, /tmp should never be exported over NFS, especially with world-writable permissions. If NFS export of temporary directories is necessary, restrict access to trusted hosts only and enforce strict permission controls. Implement network segmentation and firewall rules to limit access to NFS services to authorized systems. Regularly audit NFS exports and permissions to detect and remediate insecure configurations. Additionally, monitor network traffic and system logs for unusual access patterns to the /tmp directory. Consider migrating to newer versions of Navio NC or IBM AIX that do not have this vulnerability or provide better security controls. Finally, educate system administrators on secure NFS configuration best practices to prevent similar issues.