CVE-2024-43870 is a vulnerability in the Linux kernel's perf subsystem, specifically related to event handling during task exit. The perf subsystem is used for performance monitoring and profiling in Linux. The vulnerability arises from improper handling of event callbacks in the task_work engine when a task is scheduled out and subsequently exits. When a task is scheduled out, pending SIGTRAP signal deliveries are deferred to the target task upon resuming to userspace via task_work. However, if adding an event's callback to the task_work engine fails, this failure is ignored. Since the final call for event exit occurs after task_work has been closed, there is a small window where pending SIGTRAP signals can be queued but ignored, causing a leak in the event's reference count. This leak means that the event is never properly released when the task exits, leading to resource leakage within the kernel. The technical scenario involves preemption between tasks and interrupt requests (IRQs) that cause the event's reference count to increase unexpectedly, preventing the event from being freed. The fix involves adding proper error handling for task_work_add() calls to ensure that failures are not ignored and resources are correctly released. This vulnerability affects multiple versions of the Linux kernel as indicated by the affected commit hashes, and it was published on August 21, 2024. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, this vulnerability could lead to resource leaks in Linux systems running vulnerable kernel versions, potentially degrading system performance or causing denial of service (DoS) conditions over time. Since the perf subsystem is widely used for performance monitoring and debugging, especially in enterprise and cloud environments, the leak could affect servers, workstations, and embedded devices running Linux. Resource leakage in kernel space can accumulate, leading to system instability or crashes, which could disrupt critical business operations. Although this vulnerability does not directly allow privilege escalation or remote code execution, the resulting instability could be exploited as part of a larger attack chain or cause operational disruptions. Organizations relying on Linux-based infrastructure for critical services, including cloud providers, telecommunications, and industrial control systems, may face increased risk of downtime or degraded performance if the vulnerability is not addressed promptly.

European organizations should prioritize updating their Linux kernels to versions that include the patch for CVE-2024-43870 as soon as it becomes available. Until patches are applied, organizations should monitor system logs for unusual perf subsystem warnings or errors that might indicate resource leaks. Limiting the use of perf monitoring tools on production systems or isolating them in controlled environments can reduce exposure. Additionally, organizations should implement robust kernel-level monitoring to detect abnormal resource consumption patterns that could signal exploitation or impact from this vulnerability. For environments where kernel updates are delayed due to operational constraints, consider applying kernel live patching solutions if supported. Finally, ensure that system administrators and security teams are aware of this vulnerability and incorporate it into vulnerability management and patching workflows.