The Linux kernel’s Ceph filesystem contains a reference‑counting flaw (CWE‑911) that arises when a write operation is aborted during an unmount. The flawed logic retains an inode writeback reference that is never released, keeping the inode’s reference count non‑zero. This leads to a kernel BUG, manifested by the message "VFS: Busy inodes after unmount of ceph" and a fault at fs/super.c:650.

The vulnerability exists in the Linux kernel particularly in the Ceph filesystem support; no specific kernel release numbers were enumerated, so all unpatched kernels that use Ceph are potentially impacted.

The CVSS score of 7.8 indicates a high severity flaw, but the EPSS score shows a very low exploitation probability (<1%) and the vulnerability is not listed in CISA's KEV catalog. The bug appears to be triggered during an unmount operation when a Ceph writeback is aborted, an attack scenario inferred from the description; an attacker would need privileged access to the system to perform the dismount while a write is in progress, making exploitation difficult. Though the flaw can lead to a kernel crash with a VFS BUSY inode error, the practicality of exploitation remains limited under normal conditions.