The vulnerability resides in the Linux kernel’s btrfs filesystem handling of inline extents. When an inline extent cannot be created due to a lack of space, the code incorrectly frees the reserved qgroup data during the fallback to the copy‑on‑write path. This frees resources that will still be used, causing a bookkeeping mismatch between the reservation and the actual data usage. The resulting inconsistency can lead to allocation errors, corrupted file‑system metadata, or loss of user data. The weakness is consistent with improper resource handling (CWE‑404).

All Linux kernel releases that contain the btrfs implementation before the patch commit that introduced the fix (for example, kernel 6.19 rc1 through rc4 and any earlier mainline kernels). The issue applies to the generic Linux kernel product; no vendor‑product version ranges are specified by the CNA, but any system using an unpatched kernel with btrfs is potentially affected.

The CVSS score of 5.5 indicates moderate impact, and the EPSS score of less than 1% combined with the absence from CISA’s KEV catalog suggest that exploitation is currently unlikely to be widespread. The flaw is triggered only when a write operation to a btrfs volume fails because the filesystem has run out of space, so an attacker would need local or privileged access to create such failing write attempts. The vulnerability is not publicly documented as being actively exploited at this time.