CVE-2024-27017 is a vulnerability identified in the Linux kernel's netfilter subsystem, specifically within the nft_set_pipapo component. Netfilter is a critical framework in the Linux kernel responsible for packet filtering, network address translation (NAT), and other packet mangling. The vulnerability arises due to a race condition during netlink dump operations, where the generation mask—used to track the current view of a data structure—can be updated concurrently while a netlink dump is in progress. This causes the pipapo set backend walk iterator to lose the ability to reliably determine the correct view of the data structure it should operate on. Essentially, the iterator may read or update inconsistent or stale data because it cannot infer whether the user intends to read or modify the set. The flaw stems from insufficient synchronization and lack of explicit notation to distinguish between read and update operations during iteration. The vulnerability was addressed by adding explicit notation to specify user intent (read or update) and improving the handling of the generation mask to prevent inconsistent views during concurrent operations. The patch was contributed by Florian Westphal. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The affected versions correspond to specific Linux kernel commits prior to the patch. This vulnerability could potentially be triggered by local or remote users with the ability to interact with netfilter's nftables interface via netlink sockets, which is commonly used for firewall and packet filtering configuration and management.

For European organizations, the impact of CVE-2024-27017 could be significant depending on the deployment of vulnerable Linux kernel versions in their infrastructure. Linux is widely used across European enterprises, government agencies, and critical infrastructure, including in servers, network appliances, and embedded devices. Exploitation of this vulnerability could lead to inconsistent or corrupted state within netfilter's packet filtering rules, potentially causing denial of service (DoS) conditions by disrupting network traffic filtering or firewall operations. In worst-case scenarios, it could be leveraged as a stepping stone for privilege escalation or unauthorized manipulation of network policies, undermining network security and data confidentiality. Given that netfilter is integral to network security on Linux systems, any instability or compromise could affect availability and integrity of network services. Although no active exploits are known, the vulnerability's nature suggests that attackers with local access or the ability to send crafted netlink messages could exploit it. This risk is heightened in multi-tenant environments such as cloud providers or shared hosting platforms prevalent in Europe. Organizations relying on Linux-based firewalls or routers should be particularly vigilant. The vulnerability does not appear to require user interaction beyond the ability to send netlink messages, which may be restricted by default but could be accessible in certain configurations or through privilege escalation.

To mitigate CVE-2024-27017, European organizations should prioritize updating their Linux kernel to the patched versions that address this vulnerability. Since the issue lies in the kernel's netfilter nft_set_pipapo backend, applying the latest stable kernel releases or backported security patches from trusted Linux distributors (e.g., Debian, Ubuntu, Red Hat, SUSE) is critical. Network administrators should audit and restrict access to netlink sockets, ensuring that only authorized users and processes can interact with nftables configurations. Implementing strict access controls and monitoring netlink socket usage can reduce the attack surface. Additionally, organizations should review firewall and packet filtering configurations for anomalies or unexpected changes that could indicate exploitation attempts. For environments where immediate patching is not feasible, consider isolating vulnerable systems from untrusted networks or limiting user privileges to prevent unauthorized netlink interactions. Employing kernel security modules (e.g., SELinux, AppArmor) to enforce policies on netlink socket usage can provide an additional layer of defense. Regularly monitoring security advisories from Linux vendors and integrating vulnerability management processes will help ensure timely response to emerging threats related to this vulnerability.