A bug in the Linux kernel’s F2FS filesystem causes the free_sections counter to be over‑estimated after a segment range is freed. The logic that should reduce free_sections by the number of already‑free sections in the truncated range is omitted, leaving the kernel to believe more space is available than actually is. This inconsistency can trigger allocation failures or assertion errors when the garbage collector migrates data, potentially causing the filesystem to become unavailable. The weakness is an integer overflow (CWE-617).

The vulnerability exists in the Linux kernel implementation of the F2FS filesystem. It affects all systems that run a kernel version prior to the patch that applies this fix and use F2FS for persistent storage. Any distribution shipping such a kernel version is impacted; the exact kernel release numbers are not provided in the data so users should check whether their current kernel includes the commit that adjusts free_sections during free_segment_range.

The CVSS score of 5.5 indicates medium severity, but the EPSS score of less than 1% and exclusion from CISA’s KEV catalog point to a low probability of exploitation. The flaw is local in nature, requiring the ability to manipulate file‑system metadata—normally through privileged or local actions. The likely attack vector is local privileged access that can trigger the faulty counter to force allocation failures or crash the filesystem, leading to denial of service for applications that rely on the affected storage. No public exploit has been reported, so immediate exploitation is unlikely, but the impact warrants patching.