CVE-2022-48910 is a vulnerability in the Linux kernel's IPv6 networking stack related to improper handling of multicast group state transitions when network interfaces go down or IPv6 is disabled. Specifically, the issue arises because the kernel calls the function ipv6_mc_down() multiple times without corresponding calls to ipv6_mc_up() when the network device's state toggles between down and IPv6 disabled states. This leads to a memory leak where the kernel allocates new entries in the idev->mc_tomb list for each multicast group the interface subscribes to, without freeing previous allocations. The leak affects the struct ifmcaddr6 objects representing multicast group memberships. The vulnerability can be reproduced by repeatedly bringing an interface up and down while toggling IPv6 disablement, or by joining multicast groups via IPV6_ADD_MEMBERSHIP or enabling forwarding on the interface. The root cause is that the kernel does not correctly track the IPv6 state readiness of the interface, causing repeated calls to ipv6_mc_down() without matching ipv6_mc_up() calls. The fix involves tracking the IPv6 ready state and only calling ipv6_mc_down() when the state changes from ready to not ready. This vulnerability does not appear to allow remote code execution or privilege escalation directly but causes resource exhaustion through memory leaks in kernel memory structures related to IPv6 multicast. No known exploits in the wild have been reported, and no CVSS score has been assigned yet.

For European organizations, this vulnerability primarily poses a risk of denial of service through resource exhaustion on Linux systems that heavily use IPv6 multicast networking. Servers, network appliances, and IoT devices running affected Linux kernel versions could experience kernel memory leaks leading to degraded performance or crashes if subjected to repeated interface state toggling or multicast group membership changes. This could impact critical infrastructure, telecommunications, cloud service providers, and enterprises relying on Linux-based networking equipment. Although exploitation requires local access or the ability to trigger interface state changes, attackers with such access could cause instability or outages. The vulnerability does not directly expose confidential data or allow privilege escalation but could be leveraged as part of a broader attack chain to disrupt services. Given the widespread use of Linux in European data centers, telecom networks, and industrial control systems, the impact could be significant in environments with IPv6 multicast usage.

1. Apply the official Linux kernel patches that address CVE-2022-48910 as soon as they become available from trusted sources or Linux distributions. 2. Monitor network interface state changes and IPv6 configuration changes to detect unusual patterns of toggling that could trigger the leak. 3. Limit unprivileged user ability to join IPv6 multicast groups or disable unnecessary multicast group memberships on critical systems. 4. Implement system-level resource monitoring to detect abnormal kernel memory usage indicative of leaks. 5. Where possible, restrict local access to systems to trusted users to reduce risk of exploitation. 6. For environments with critical uptime requirements, consider temporarily disabling IPv6 multicast features if feasible until patches are applied. 7. Regularly update Linux kernel versions to incorporate security fixes and improvements in network stack robustness.