A kernel bug was found in the huge page unmapping routine. When a huge page is mapped in both a parent and child, the unmap handler reduces the reservation counter without first verifying that the mapping is the last reference. The counter can underflow, corrupting memory reservation bookkeeping and potentially leading to incorrect memory accounting, resource exhaustion, or a kernel crash. This flaw is an integer underflow vulnerability, classified as CWE‑191.

All Linux kernel builds released before the patch commit are affected, regardless of distribution. The flaw is present in the generic Linux kernel incorporated the bug‑fix commit that guards the reservation decrement.

The CVSS score of 4.7 places the vulnerability in the low‑medium range, indicating limited impact compared to more severe kernel bugs. Exploitation requires a process that can map and unmap huge pages, which typically demands at least root privileges or the CAP_SYS_ADMIN capability. The likely attack vector is local privilege escalation; this inference is derived from the fact that mapping/unmapping huge pages is a privileged operation, not stated explicitly in the advisory. No remote exploitation path has been identified. The EPSS score is < 1%, indicating a very low likelihood of exploitation, and the vulnerability is not listed in the CISA KEV catalog.