CVE-2022-49799 is a vulnerability identified in the Linux kernel's tracing subsystem, specifically within the function register_synth_event(). The issue arises when the function set_synth_event_print_fmt() fails during the registration process of a synthetic trace event. In this failure scenario, the kernel erroneously calls both trace_remove_event_call() and unregister_trace_event(), resulting in the trace_event_call invoking __unregister_trace_event() twice on the same event. This double unregistration leads to a wild memory access, which is an out-of-bounds or use-after-free memory access, potentially causing kernel instability or crashes. The vulnerability manifests as a general protection fault, often triggered by non-canonical memory addresses, as evidenced by kernel address sanitizer (KASAN) reports and kernel panic traces. The root cause is a lack of proper state tracking to prevent the second call to __unregister_trace_event() after the first has already been executed. The fix involves adding a check to ensure that the second unregister call is skipped if the first has already occurred, thereby preventing the wild memory access. This vulnerability affects Linux kernel versions prior to the patch and is related to kernel tracing infrastructure, which is widely used for debugging and performance monitoring. 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, especially those utilizing kernel tracing features for diagnostics or monitoring. Exploitation could lead to kernel crashes or denial of service (DoS), impacting system availability and potentially causing disruptions in critical infrastructure, cloud services, and enterprise environments relying on Linux servers. While direct privilege escalation or remote code execution is not explicitly indicated, the instability caused by wild memory access could be leveraged in complex attack chains. Organizations in sectors such as finance, telecommunications, manufacturing, and government, which heavily depend on Linux-based systems, may experience operational interruptions. Additionally, embedded Linux devices used in industrial control systems or IoT deployments across Europe could be affected if they run unpatched kernels. The absence of known exploits reduces immediate risk, but the vulnerability's nature warrants prompt attention to prevent future exploitation attempts.

European organizations should prioritize updating their Linux kernels to versions where this vulnerability is patched. Specifically, they should apply the latest stable kernel releases that include the fix preventing double unregistration in register_synth_event(). For environments where immediate patching is challenging, disabling or limiting the use of synthetic trace events and kernel tracing features can reduce exposure. System administrators should audit kernel modules and tracing configurations to identify usage of the affected functions. Employing kernel address sanitizers (KASAN) or similar runtime memory error detectors in testing environments can help detect related issues proactively. Additionally, organizations should implement robust monitoring for kernel crashes or unusual system behavior indicative of wild memory access. Coordinating with Linux distribution maintainers to ensure timely patch deployment and verifying kernel versions across infrastructure is critical. For embedded devices, firmware updates incorporating patched kernels should be prioritized. Finally, maintaining strict access controls to kernel debugging and tracing interfaces will limit the potential for exploitation by unauthorized users.