The vulnerability originates in the Linux kernel’s task memory mapping subsystem. When a process performs a PAGEMAP_SCAN ioctl with the PM_SCAN_WP_MATCHING flag on a hugetlb virtual memory area, the scan holds a read lock on the VMA while later attempting to write‑protect an unpopulated page via a path that acquires the write lock on the same VMA. This reentrancy causes the thread to block on a down_write() call for a lock it already holds, resulting in an unkillable deadlock and a permanent hang of the calling thread. The effect is a local denial of service because the process that issued the ioctl cannot recover until the system is reset.

The flaw is confined to the Linux kernel source tree. Any running kernel that has not integrated the patch described in the commit references is potentially impacted. The advisory does not specify a version range, so all kernels prior to the patch are presumed vulnerable until the update is applied.

The EPSS score is reported as less than 1 % and the vulnerability is not listed in the CISA KEV catalog, indicating no widespread exploitation has been observed. Exploitation requires local access to a process that can invoke the PAGEMAP_SCAN ioctl on a hugetlb VMA; typical user‑level access to that process suffices. The CVSS base score of 5.5 indicates moderate severity. Given the low EPSS and absence from KEV, the chance of widespread attack is low, but the vulnerability remains a notable local denial of service for affected systems.