CVE-2022-49362 is a high-severity vulnerability identified in the Linux kernel's NFS server implementation (nfsd). The issue is a use-after-free flaw in the function nfsd_file_put(), specifically related to the handling of nfsd_file_put_noref(). The vulnerability arises because nfsd_file_put_noref() can free the nf pointer, but the code erroneously dereferences nf immediately after the function returns, leading to a use-after-free condition. This type of vulnerability (CWE-416) can cause memory corruption, potentially allowing an attacker to execute arbitrary code, escalate privileges, or cause denial of service by crashing the kernel. The CVSS 3.1 score of 7.8 reflects a high severity with a vector indicating local attack vector (AV:L), low attack complexity (AC:L), requiring low privileges (PR:L), no user interaction (UI:N), unchanged scope (S:U), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). The vulnerability affects specific Linux kernel versions identified by commit hashes, indicating it is present in certain kernel builds prior to the fix. Although no known exploits are currently reported in the wild, the nature of the flaw and its impact make it a significant risk for systems running vulnerable Linux kernels with NFS server enabled. The flaw could be exploited by a local attacker with some privileges to cause kernel memory corruption, potentially leading to privilege escalation or system instability. The patch details are not provided in the data, but the vulnerability has been officially published and recognized by CISA, indicating the importance of timely remediation.

For European organizations, this vulnerability poses a substantial risk, especially for those relying on Linux servers running NFS services, which are common in enterprise environments for file sharing and storage. Exploitation could lead to unauthorized access to sensitive data, disruption of critical services, or full system compromise. Given the high impact on confidentiality, integrity, and availability, organizations handling sensitive or regulated data (e.g., financial institutions, healthcare providers, government agencies) could face severe operational and compliance consequences. The local attack vector means that attackers need some level of access to the system, which could be achieved through compromised user accounts or insider threats. The vulnerability could also be leveraged as part of a multi-stage attack to escalate privileges and move laterally within networks. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate it, as proof-of-concept exploits could emerge. Therefore, European organizations should prioritize patching vulnerable Linux kernels and auditing NFS server usage to mitigate potential exploitation.

1. Apply the official Linux kernel patches that address CVE-2022-49362 as soon as they become available from trusted sources or Linux distribution vendors. 2. If patching is delayed, consider disabling the NFS server service on affected systems where it is not essential to reduce the attack surface. 3. Restrict local user privileges to minimize the number of users who can execute code or access NFS services locally. 4. Implement strict access controls and monitoring on systems running NFS to detect unusual activities that could indicate exploitation attempts. 5. Employ kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR) and Control Flow Integrity (CFI) to reduce exploitation success. 6. Regularly audit and update Linux kernel versions to ensure all security patches are applied promptly. 7. Use intrusion detection systems (IDS) and endpoint detection and response (EDR) tools to identify potential exploitation behaviors related to kernel memory corruption. 8. Educate system administrators about the risks of local privilege escalation vulnerabilities and the importance of limiting local access and promptly applying security updates.