The Linux kernel’s freeze/unfreeze logic has a logical error: when a nested thaw succeeds, the function returns -EINVAL instead of 0. This misleads callers into thinking the operation failed, but the freeze reference count remains elevated. Consequently, the affected block device stays in a frozen state and can never be mounted again, effectively locking the device and disrupting access to the filesystem. The flaw is a resource‑management error that leads to a permanent resource leak.

All Linux kernel releases starting from 6.8 that have not yet applied commit 7366f8b6fc6a. The flaw lives in the core filesystem code and therefore affects every distribution that builds its kernel from this source tree, including mainstream distributions such as Ubuntu, Debian, CentOS, Fedora and others, until the protective commit is included.

An attacker capable of executing the freeze and thaw sequence can trigger the defect by using fsfreeze and device‑mapper calls that perform nested freeze/thaw operations. The defect is local in nature; no remote code execution or elevated privileges are required by the description, though the operations involved typically need the ability to perform device‑mapper commands. The CVSS score of 5.5 indicates moderate severity, and the EPSS score is < 1%, reflecting a very low likelihood of exploitation. The vulnerability is not listed in CISA’s KEV catalog. The impact is a denial‑of‑service that locks the block device until the system is rebooted or the device is recreated.