CVE-2024-35864 is a recently disclosed vulnerability in the Linux kernel affecting the SMB (Server Message Block) client implementation. Specifically, the issue arises in the smb2_is_valid_lease_break() function, where a potential Use-After-Free (UAF) condition can occur. This vulnerability is related to the handling of SMB sessions that are in the process of being torn down, identified by the status SES_EXITING. The flaw allows the kernel to access memory that has already been freed, which can lead to undefined behavior including kernel crashes or potentially arbitrary code execution in kernel context. The fix involves skipping sessions marked as SES_EXITING to prevent the UAF condition. While no known exploits are currently reported in the wild, the vulnerability affects the Linux kernel versions identified by the given commit hashes. Since the SMB protocol is widely used for file sharing and network communication, especially in enterprise environments, this vulnerability could be leveraged by an attacker with network access to the SMB client to destabilize or compromise the system. The absence of a CVSS score suggests this is a newly published issue, and its severity must be assessed based on technical characteristics and potential impact.

For European organizations, the impact of CVE-2024-35864 could be significant, especially for those relying heavily on Linux-based systems for file sharing and network services using SMB. The vulnerability could allow attackers to cause denial of service by crashing the kernel or potentially escalate privileges if exploitation leads to arbitrary code execution. This could disrupt critical business operations, data availability, and integrity. Organizations in sectors such as finance, manufacturing, government, and telecommunications, which often use Linux servers and SMB for internal and external communications, could face operational interruptions or data breaches if exploited. Moreover, the vulnerability could be used as a foothold for lateral movement within networks, increasing the risk of broader compromise. The lack of known exploits currently reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits following public disclosure.

European organizations should promptly apply the available Linux kernel patches that address this vulnerability. Since the fix involves skipping sessions in SES_EXITING state to prevent UAF, upgrading to the patched kernel versions is critical. Network administrators should also consider restricting SMB client access to trusted networks only, using firewall rules and network segmentation to limit exposure. Monitoring SMB client activity for unusual session teardown behavior could help detect exploitation attempts. Additionally, organizations should ensure that their incident response and patch management processes are agile enough to respond quickly to kernel vulnerabilities. For environments where immediate patching is challenging, temporary mitigations such as disabling SMB client functionality or isolating vulnerable systems may reduce risk. Regular backups and system integrity monitoring will help mitigate the impact of potential exploitation.