In the Linux kernel’s btrfs module, the zstd compression subsystem can lose a wakeup signal when it fails to allocate a workspace. A writer that waits for a free workspace may enter an infinite sleep in the TASK_UNINTERRUPTIBLE state, preventing the thread from running and causing system resources to be tied up. This flaw does not provide a local or remote code execution path, but it can lead to a denial of service by stalling processes that rely on zstd compression workspaces.

The issue affects all Linux kernel releases that include the btrfs file system with zstd compression support. It applies broadly to all Linux distributions that ship the original kernel code before the fix was merged. No specific version list is provided, so any kernel in the affected series is potentially vulnerable.

The vulnerability cannot be triggered remotely; it requires a local user or an attacker with local code execution privileges to invoke btrfs operations that cause workspace allocation. The CVSS score is not disclosed, EPSS data is unavailable, and the flaw is not in the CISA KEV catalog, indicating a lower likelihood of widespread exploitation. However, within a local environment, the bug can result in hung processes and reduced system availability, so the risk is considered moderate for systems that rely heavily on btrfs zstd compression.