The vulnerability is caused by a circular lock dependency in the Linux kernel’s ext4 filesystem. In ext4_ext_migrate, the code acquires the s_writepages_rwsem read‑write semaphore and then attempts to perform inode eviction while sb_internal is held. The temporary inode’s eviction later tries to re‑acquire s_writepages_rwsem, but the write lock remains held, resulting in a deadlock that stalls the thread and can freeze the entire kernel. This lock ordering flaw provides a classic deadlock scenario that effectively denies system availability.

All Linux kernel builds that ship the ext4 filesystem and include the vulnerable ext4_ext_migrate path before the referenced commits. This encompasses mainstream distributions whose kernels have not yet incorporated the patch that moves iput(tmp_inode) after ext4_writepages_up_write(). The version range is unspecified, but any build prior to the listed commit references is affected.

The CVSS score is 5.5, indicating moderate severity. The EPSS score of <1% shows a very low exploitation probability. KEV status is not listed. The attack vector is local or requires kernel privilege, as it involves invoking ext4 migration via ioctl or triggering concurrent orphan cleanup operations. While the impact is a denial of service, the absence of public exploitation evidence and the need for specific concurrent kernel activity suggest a moderate risk, warranting pre‑emptive action.