The btrfs zoned filesystem suffered a deadlock between metadata writeback and transaction commit. During the writeback loop the guard lock \"zoned_meta_io_lock\" was held across a call that could block on a transaction commit, while the commit path also required the same lock. The resulting circular wait caused the system to hang in certain workloads, such as those exercised by fstests generic/475, effectively denying service to the affected system. This concurrency flaw, based on improper lock usage, results in a deadlock that halts kernel activity.

Any Linux kernel that implements btrfs with zoned mode, from the generic kernel repository before the safeguard was merged. The specific kernel release containing the patch is not enumerated in the provided data; it is present in the recent mainline after commit 18577e77c2c8adaadf1f7c6e9bcd1c0b14e5dcdd. All distributions shipping an unpatched kernel or a kernel that still enables zoned btrfs are therefore impacted.

The CVSS score of 7.5 combined with a low EPSS (<1%) indicates a moderate to high severity vulnerability that is unlikely to be widely exploited. It is not listed in the CISA KEV catalog. The principal risk is operational: a system experiencing intensive metadata writes on a zoned btrfs volume could hang when a transaction commit requests the same locked resource, causing a denial of service. The likely attack vector is internal; an attacker who can generate or manipulate large metadata workloads on a zoned btrfs filesystem could trigger the deadlock. Because the flaw resides at the kernel level and does not involve privilege escalation or information leakage, exploitation requires only the same privileges needed to interact with the filesystem.