CVE-2022-49622 is a high-severity use-after-free vulnerability in the Linux kernel's netfilter subsystem, specifically within the nf_tables component. The vulnerability arises when the netfilter verdict is set to NF_STOLEN, indicating that the packet buffer (skb) has been taken over and potentially freed by the kernel or another subsystem. Despite this, the kernel code may still attempt to access fields within the skb, such as skb->nf_trace and skb->mark, when packet tracing is enabled. This leads to a use-after-free condition, where the kernel accesses memory that has already been freed, resulting in undefined behavior that can include kernel crashes, data corruption, or potential privilege escalation. The vulnerability is triggered during tracing operations that involve computing a trace ID and dumping packet payloads. The fix involves caching the skb->nf_trace value in the trace state structure, skipping access to skb->mark when the verdict is NF_STOLEN, precomputing the trace ID to avoid accessing freed memory, and only dumping the packet when the verdict is not NF_STOLEN. The vulnerability is identified as CWE-416 (Use After Free) and has a CVSS v3.1 base score of 7.8, indicating high severity. Exploitation requires local privileges (AV:L), low attack complexity (AC:L), and privileges (PR:L), but no user interaction (UI:N). No known exploits are currently reported in the wild. The affected versions correspond to specific Linux kernel commits prior to the patch. This vulnerability impacts all Linux distributions using affected kernel versions with netfilter nf_tables and tracing enabled, which is common in firewall and packet filtering configurations.

For European organizations, this vulnerability poses a significant risk to the confidentiality, integrity, and availability of systems running vulnerable Linux kernels with netfilter nf_tables enabled and packet tracing active. Exploitation could allow a local attacker or a compromised process with limited privileges to execute arbitrary code in kernel space, potentially leading to privilege escalation and full system compromise. This could disrupt critical infrastructure, enterprise servers, and cloud environments prevalent in Europe. The use-after-free condition could also cause kernel panics and denial of service, impacting service availability. Given the widespread use of Linux in European data centers, telecommunications, and government systems, the vulnerability could affect a broad range of sectors. Although no public exploits are known, the ease of exploitation and high impact necessitate urgent attention. Organizations relying on Linux-based firewalls or network appliances with tracing enabled are particularly at risk.

European organizations should immediately verify their Linux kernel versions and apply the latest security patches that address CVE-2022-49622. Since the vulnerability is tied to the nf_tables subsystem and tracing functionality, disabling packet tracing temporarily can reduce risk until patches are applied. Network administrators should audit firewall and packet filtering configurations to ensure minimal exposure. Employ kernel hardening techniques such as enabling Kernel Address Space Layout Randomization (KASLR), Kernel Page Table Isolation (KPTI), and other memory protection features to mitigate exploitation impact. Regularly monitor system logs for unusual kernel trace activity or crashes that could indicate exploitation attempts. For environments where patching is delayed, consider isolating vulnerable systems or restricting local access to trusted users only. Additionally, maintain up-to-date intrusion detection systems capable of recognizing anomalous kernel behavior related to netfilter operations.