CVE-2022-48919 is a vulnerability in the Linux kernel's CIFS (Common Internet File System) client implementation. The flaw arises from a double free race condition in the function cifs_get_root() during the mount process handled by cifs_smb3_do_mount(). Specifically, when cifs_get_root() fails, the kernel calls deactivate_locked_super(), which eventually triggers delayed_free() to free the context. However, the code erroneously proceeds to an 'out:' section in cifs_smb3_do_mount() that attempts to free the same resources again, leading to a double free. This double free can cause use-after-free conditions, as evidenced by Kernel Address Sanitizer (KASAN) reports showing invalid memory reads and frees in the kernel stack trace. The vulnerability is triggered during the mounting of SMB3 shares via CIFS, which is commonly used for network file sharing in Linux environments. The issue was identified and fixed in Linux kernel versions around 5.17.0-rc3. The vulnerability does not require user interaction but does require the ability to mount CIFS shares, which typically implies local or network-level access. The vulnerability can cause kernel memory corruption, potentially leading to system crashes (denial of service) or, in a worst-case scenario, privilege escalation or arbitrary code execution within the kernel context if exploited successfully. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The patch details are not explicitly provided in the data, but the fix involves preventing the double free by ensuring the code does not proceed to free resources twice after a mount failure.

For European organizations, the impact of CVE-2022-48919 can be significant, especially for those relying heavily on Linux servers and systems that mount SMB/CIFS shares for file storage and sharing. The vulnerability could be exploited to cause kernel crashes, leading to denial of service on critical infrastructure such as file servers, application servers, or virtual machines running Linux. In environments where attackers have network access to mount CIFS shares or local access to trigger mounts, this vulnerability could be leveraged to escalate privileges or execute arbitrary code in the kernel, compromising system integrity and confidentiality. This is particularly concerning for sectors with sensitive data such as finance, healthcare, and government agencies across Europe. Additionally, Linux is widely used in cloud and virtualized environments; thus, the vulnerability could affect cloud service providers and their customers. The lack of known exploits reduces immediate risk, but the potential for severe impact mandates prompt attention.

European organizations should take the following specific mitigation steps: 1) Immediately identify and inventory Linux systems using CIFS to mount SMB3 shares, prioritizing servers and virtual machines in critical roles. 2) Apply the latest Linux kernel updates that include the patch for CVE-2022-48919 as soon as they become available from trusted vendors or distributions. 3) Temporarily restrict or disable CIFS mounts where feasible, especially on systems exposed to untrusted networks, until patches are applied. 4) Monitor system logs for kernel errors or crashes related to CIFS mounts that may indicate attempted exploitation. 5) Implement network segmentation to limit access to CIFS services only to trusted hosts and users. 6) Employ kernel hardening and exploit mitigation techniques such as Kernel Address Sanitizer (KASAN) in testing environments to detect similar issues proactively. 7) Educate system administrators about the risks of mounting SMB shares and enforce strict access controls and authentication mechanisms for mounting operations. 8) For virtualized environments, ensure hypervisor and guest OS isolation to reduce risk of lateral movement if exploitation occurs.