CVE-2024-27013 is a vulnerability in the Linux kernel's TUN (network tunnel) device driver, specifically related to the handling of illegal packets received by the TUN device. The vulnerability arises because the vhost_worker thread, which handles virtualized network I/O, calls TUN callbacks to receive packets. When an excessive number of illegal packets are received, the function tun_do_read repeatedly dumps packet contents to the console. If the console is enabled, this excessive logging consumes significant CPU resources, potentially leading to a soft lockup—a state where the CPU is stuck in a loop and unable to perform other tasks. The root cause is the lack of rate limiting on the printing of illegal packet data. The fix involves applying the net_ratelimit mechanism to limit the rate at which packet contents are dumped, preventing CPU exhaustion. The stack trace provided shows the crash occurring in the io_serial_in function, triggered by excessive printk calls from tun_do_read. This vulnerability can be triggered remotely if an attacker can send crafted illegal packets to a vulnerable TUN device, especially in virtualized environments using vhost-net. No CVSS score is assigned yet, and no known exploits are reported in the wild. The affected versions correspond to specific Linux kernel commits identified by their hashes, indicating this is a recent kernel-level fix.

For European organizations, the impact of CVE-2024-27013 can be significant, particularly for those relying on Linux-based virtualized infrastructure or VPN solutions that use TUN devices. The vulnerability can cause denial of service (DoS) conditions by exhausting CPU resources through excessive logging, leading to system instability or crashes. This can disrupt critical services, including cloud workloads, containerized applications, and network security appliances. Organizations with high-density virtualized environments or those using vhost-net for network acceleration are at higher risk. The vulnerability does not appear to allow privilege escalation or direct data compromise but can degrade availability and operational continuity. Given the widespread use of Linux in European data centers, telecom infrastructure, and enterprise environments, unpatched systems could face service interruptions. Additionally, the vulnerability could be exploited as part of a multi-stage attack to cause disruption or as a diversion while other attacks are conducted.

European organizations should prioritize patching Linux kernels to versions that include the fix for CVE-2024-27013. Specifically, they should update to kernel versions that implement net_ratelimit in tun_do_read to prevent excessive logging. For environments where immediate patching is not feasible, administrators can consider disabling console logging for TUN devices or limiting console output to reduce CPU load. Network administrators should monitor for unusual volumes of illegal packets targeting TUN devices and implement network-level filtering to block malformed or suspicious traffic. Virtualized environments using vhost-net should be closely monitored, and hypervisor security best practices applied. Additionally, organizations should audit their use of TUN devices and vhost-net to ensure minimal exposure and apply strict access controls. Logging and monitoring solutions should be tuned to detect signs of CPU exhaustion or soft lockups related to this vulnerability.