CVE-2022-41787 is a high-severity vulnerability affecting multiple versions of F5 BIG-IP DNS, specifically versions 13.1.x through 17.0.x prior to their respective patch releases. The issue arises when a DNS profile is configured on a virtual server with DNS Express enabled. Under these conditions, specially crafted, undisclosed DNS queries that utilize DNSSEC can trigger a NULL pointer dereference (CWE-476) within the Traffic Management Microkernel (TMM) component of BIG-IP. This dereference causes the TMM process to terminate unexpectedly, resulting in a denial of service (DoS) condition. The vulnerability does not impact confidentiality or integrity but severely affects availability by crashing the core traffic management process, which is critical for DNS resolution and load balancing functions. The CVSS v3.1 base score is 7.5 (high), reflecting network attack vector, low attack complexity, no privileges or user interaction required, and a scope limited to availability impact. No known exploits in the wild have been reported to date. The vulnerability affects a broad range of BIG-IP DNS versions, indicating that many organizations using F5 BIG-IP appliances with DNS Express enabled are potentially vulnerable if not patched. The lack of patch links in the provided data suggests that organizations should consult F5’s official advisories for updated firmware versions that address this issue.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on F5 BIG-IP DNS appliances for critical DNS resolution and traffic management services. The forced termination of the TMM process can lead to service outages, disrupting internal and external DNS queries, which may cascade into broader network availability issues. This can affect web services, cloud applications, and any infrastructure dependent on DNS resolution. Given the essential role of DNS in network operations, such outages can result in operational downtime, loss of productivity, and potential financial losses. Additionally, organizations in sectors with stringent availability requirements—such as finance, telecommunications, healthcare, and government—may face compliance and reputational risks if service disruptions occur. The vulnerability’s exploitation does not require authentication or user interaction, increasing the risk of remote exploitation by attackers scanning for vulnerable BIG-IP DNS instances. Although no exploits are currently known in the wild, the ease of triggering the DoS condition makes this a credible threat vector for denial-of-service attacks targeting European enterprises.

European organizations should immediately verify if their F5 BIG-IP DNS deployments are running affected versions with DNS Express enabled on virtual servers. They should prioritize upgrading to the fixed versions released by F5: 17.0.0.1 or later, 16.1.3.1 or later, 15.1.6.1 or later, 14.1.5.1 or later, and 13.1.5.1 or later. In environments where immediate patching is not feasible, organizations should consider temporarily disabling DNS Express on vulnerable virtual servers to mitigate the risk of TMM crashes. Network-level mitigations such as rate limiting or filtering DNS queries with DNSSEC flags from untrusted sources can reduce exposure. Monitoring TMM process stability and implementing alerting for unexpected restarts can provide early detection of exploitation attempts. Additionally, organizations should review their network segmentation and access controls to limit exposure of BIG-IP DNS services to untrusted networks. Regularly consulting F5 security advisories and subscribing to vulnerability notification services will ensure timely awareness of patches and related threats.