The Linux kernel contained a regression where the .mmap_prepare() routine could leave a reference count increment unreleased. The commit that reoriented generic_file_*mmap() calls back to .mmap_prepare() was partially reverted to avoid a situation where a merge or allocation failure might happen after the call, leading to a refcount leak. The resulting leak could, over time, consume kernel resources and potentially cause a denial‑of‑service scenario if unchecked. This weakness maps to the classic memory‑leak category.

Systems running the Linux kernel are impacted, regardless of distribution, as the issue resides in core kernel source. No specific version range is supplied, so any kernel that applied the commit in question before the series of patches including this revert may be vulnerable.

With no published CVSS or EPSS score and no KEV listing, the exact risk remains undefined. The developers identified a refcount leak that could lead to resource exhaustion; however, no public exploit evidence is known. The absence of EPSS data does not confirm low exploitation probability, but recent kernel fixes suggest it is likely mitigated in newer releases. Until the fix is applied, administrators should treat the possibility of a denial‑of‑service vector as a concern.