CVE-2022-48950 is a use-after-free (UaF) vulnerability in the Linux kernel's perf subsystem, specifically related to the function perf_pending_task(). The perf subsystem is used for performance monitoring and profiling in Linux. The vulnerability arises because perf_pending_task() can be executed after the associated perf_event structure has been freed. There are two distinct scenarios causing this issue: first, the task_work associated with the event was already queued before the event was destroyed; second, the destruction process itself queues additional task_work despite the event being in the process of termination. The first scenario cannot be mitigated by task_work_cancel() because perf_release(), which frees the event, may itself be called from a task_work context, leaving the current task_works list empty and unable to locate the perf_pending_task() entry. The fix involves extending the lifetime of the perf_event to cover the duration of the task_work, preventing premature freeing. The second scenario is addressed by reordering the state transitions of the event, ensuring it passes through STATE_OFF before reaching STATE_DEAD, thereby preventing task_work from being queued during teardown. This vulnerability could lead to kernel crashes or potentially arbitrary code execution if exploited, as use-after-free bugs can corrupt kernel memory. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, this vulnerability poses a risk primarily to systems running vulnerable Linux kernel versions with perf enabled. The perf subsystem is widely used in server environments, development, and performance monitoring tools. Exploitation could lead to denial of service through kernel crashes or privilege escalation if an attacker can trigger the use-after-free condition. This is particularly concerning for critical infrastructure, cloud service providers, and enterprises relying on Linux-based servers. The impact on confidentiality, integrity, and availability could be significant if attackers leverage this flaw to gain kernel-level access. Given the complexity of exploitation and the requirement to trigger specific kernel task_work conditions, the attack surface is somewhat limited but still relevant for high-value targets. European organizations in sectors such as finance, telecommunications, and government, which often use Linux extensively, should be vigilant. Additionally, the vulnerability could affect embedded Linux devices used in industrial control systems, increasing the risk to operational technology environments.

Organizations should promptly apply the official Linux kernel patches that address CVE-2022-48950 once available. Until patches are deployed, it is advisable to limit untrusted user access to systems running vulnerable kernels, as exploitation requires triggering kernel task_work queues. Monitoring kernel logs for unusual perf subsystem activity may help detect attempts to exploit this vulnerability. Disabling or restricting the use of perf_event for unprivileged users can reduce risk, as perf requires elevated privileges for many operations. For environments using containerization or virtualization, ensure that host kernels are patched, as container escapes via kernel vulnerabilities are a known risk. Additionally, conduct thorough testing of kernel updates in staging environments to avoid service disruptions. Security teams should update intrusion detection and prevention systems with signatures related to this vulnerability once they become available. Finally, maintain a robust patch management process to ensure timely updates of Linux kernels across all systems.