CVE-2026-23225

A flaw was found in the Linux kernel. A local user can exploit a race condition in the sched/mmcid mode switch path. This occurs when a task exits with a specific flag (MM_CID_TRANSIT) still set, leading to an incorrect assumption that the Context ID (CID) is CPU-owned. This can result in an out-of-bounds bit operation, causing the kernel to crash, leading to a Denial of Service (DoS). In a worst-case scenario, this flaw could also lead to kernel memory corruption, potentially impacting system integrity and confidentiality.

A local race in the sched mmcid mode switch path can lead to an out of bounds bit operation when a task exits with the MM_CID_TRANSIT flag still set and the code incorrectly assumes the CID is CPU owned. This can cause clear_bit to be called with an extremely large bit index which can crash the kernel and may corrupt kernel memory. For the CVSS the PR is L because a normal local user can create and exit tasks and potentially hit the timing window during CID mode transitions. The issue is not network reachable and requires local execution on the host. Impact is at least denial of service due to a kernel crash. A conservative worst case also considers possible integrity and confidentiality impact if the out of bounds write can be steered into sensitive memory.

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.