CVE-2024-26219 is a high-severity vulnerability identified in Microsoft Windows 10 Version 1809, specifically affecting the HTTP.sys component. The vulnerability is classified as a NULL Pointer Dereference (CWE-476), which occurs when the system attempts to access or dereference a pointer that is set to NULL, leading to a crash or denial of service (DoS). HTTP.sys is a kernel-mode device driver that handles HTTP requests for Windows, playing a critical role in network communications and web services hosted on Windows machines. Exploitation of this vulnerability requires no authentication and no user interaction, making it remotely exploitable over the network (Attack Vector: Network). An attacker can send specially crafted HTTP requests to a vulnerable system, causing the HTTP.sys driver to dereference a NULL pointer, resulting in a system crash or reboot, thereby denying legitimate users access to services hosted on the affected machine. The CVSS v3.1 base score is 7.5, reflecting a high severity due to the ease of exploitation (low attack complexity), no privileges required, and the impact being limited to availability (no confidentiality or integrity impact). There are no known exploits in the wild at the time of publication, and no official patches have been linked yet, which suggests that affected organizations should prioritize mitigation and monitoring. The vulnerability affects Windows 10 Version 1809 (build 10.0.17763.0), which is an older version of Windows 10, but still in use in some environments, especially in legacy systems or specialized industrial setups.

For European organizations, this vulnerability poses a significant risk to availability of critical services, especially those relying on Windows 10 Version 1809 servers or endpoints that handle HTTP traffic via HTTP.sys. Potential impacts include disruption of web services, internal applications, or any network-facing service that depends on HTTP.sys, leading to downtime and operational interruptions. This can affect sectors such as manufacturing, healthcare, finance, and public administration, where legacy Windows 10 systems might still be in use. The denial of service could be leveraged as part of a larger attack campaign to cause disruption or as a diversion for other malicious activities. Given the lack of confidentiality or integrity impact, data breaches are unlikely directly from this vulnerability, but service outages can have cascading effects on business continuity and reputation. Organizations with critical infrastructure or those providing essential services in Europe must be particularly vigilant, as service availability is often regulated and disruptions can have legal and financial consequences.

1. Immediate identification and inventory of all systems running Windows 10 Version 1809 within the organization, focusing on those exposed to external networks or handling HTTP traffic. 2. Apply any available security updates or patches from Microsoft as soon as they are released; monitor Microsoft security advisories closely. 3. If patching is not immediately possible, implement network-level mitigations such as blocking or filtering suspicious HTTP traffic patterns that could trigger the vulnerability, using Web Application Firewalls (WAFs) or Intrusion Prevention Systems (IPS) with custom rules. 4. Limit exposure of vulnerable systems by restricting inbound HTTP traffic to trusted sources only, using network segmentation and access control lists. 5. Monitor system logs and network traffic for unusual HTTP requests or signs of repeated crashes/reboots indicative of exploitation attempts. 6. Consider upgrading affected systems to a more recent and supported Windows version where this vulnerability is not present, to reduce long-term risk. 7. Develop and test incident response plans specifically for denial of service scenarios affecting HTTP.sys to minimize downtime and recovery time. 8. Educate IT and security teams about the vulnerability specifics to ensure rapid detection and response.