CVE-2026-98536

A flaw was found in the Linux kernel's writeback subsystem. This vulnerability can lead to a Denial of Service (DoS) when the routine responsible for cleaning up offline control group writeback structures fails to report a quiescent state during extended cleanup passes under certain preemption configurations. A local user can trigger conditions that cause this prolonged draining to stall internal Read-Copy Update (RCU) synchronization mechanisms and block dependent system processes. This prolonged blockage can cause affected tasks to hang indefinitely, ultimately triggering the kernel hung task detector and crashing the system.

This vulnerability is rated as Moderate impact because triggering the denial of service requires local access alongside high volumes of control group writeback activity and concurrent RCU-synchronized operations, limiting the scope of exploitation to system availability without threatening data integrity or confidentiality. On Red Hat Enterprise Linux systems running affected kernels with dynamic preemption, prolonged cgroup cleanup passes can delay Tasks-RCU grace periods and stall processes waiting in uninterruptible sleep. System disruption typically manifests only when long-running writeback queue drains coincide with tracing or subsystem unregistration, rather than during normal baseline workloads.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.