CVE-1999-0849 is a medium-severity denial of service (DoS) vulnerability affecting specific versions of the BIND (Berkeley Internet Name Domain) DNS server software, specifically versions 4.9.5 through 4.9.7 and 8.1 through 8.2.1. The vulnerability arises from the handling of the 'maxdname' parameter within the named daemon, which is responsible for DNS resolution. An attacker can exploit this flaw remotely without authentication by sending specially crafted DNS queries that manipulate the maxdname setting, causing the named process to crash or become unresponsive. This results in a denial of service condition, disrupting DNS resolution services provided by the affected server. The CVSS v2 score of 5.0 reflects that the attack vector is network-based, requires no authentication, and impacts availability only, with no confidentiality or integrity impact. No patch is available for this vulnerability, and no known exploits have been reported in the wild, likely due to the age of the affected versions and the evolution of BIND since then. However, the vulnerability remains relevant for legacy systems still running these outdated BIND versions. Since DNS is a critical infrastructure component, disruption can have cascading effects on network operations and service availability.

For European organizations, the impact of this vulnerability primarily concerns availability. Organizations relying on legacy BIND versions for DNS services may experience service outages if targeted, leading to potential downtime of internal and external services dependent on DNS resolution. This can affect web services, email delivery, and other network-dependent applications, causing operational disruptions and potential financial losses. While the vulnerability does not compromise data confidentiality or integrity, the denial of service can degrade trust in IT infrastructure reliability. Given the critical role of DNS in network operations, even temporary outages can impact business continuity, especially for sectors like finance, telecommunications, and government services where uptime is crucial. Additionally, organizations with legacy systems may face challenges in incident response and recovery due to the lack of available patches.

Since no official patch is available for this vulnerability, European organizations should prioritize upgrading to supported and patched versions of BIND that address this and other known vulnerabilities. If upgrading is not immediately feasible, organizations should implement network-level mitigations such as restricting access to DNS servers from untrusted networks using firewalls and access control lists, thereby limiting exposure to potential attackers. Deploying DNS rate limiting and anomaly detection can help identify and mitigate suspicious query patterns targeting maxdname or other parameters. Additionally, organizations should consider deploying redundant DNS infrastructure with failover capabilities to maintain service availability in case of an attack. Regularly auditing DNS server configurations and monitoring logs for unusual activity can provide early warning signs of exploitation attempts. Finally, migrating to alternative DNS software with active support and security updates can reduce risk exposure.