The Linux kernel contains a flaw in the page_ext iteration API that allows the iterator to advance past the last valid page frame number. When memory is added online, the iterator can reference a PFN that has not yet been initialized, causing a page_ext_lookup to dereference a NULL pointer. This results in a kernel panic, leading to denial of service for the system.

All Linux kernel implementations using the C source path "mm/page_ext" before the patch are affected. No specific product variant or version list is given, so any kernel versions that have not yet incorporated the fix are potentially vulnerable.

The flaw is a local issue that requires the ability to trigger memory hotplug, typically only available to privileged users. Attackers would need to execute the abnormal memory addition sequence, which is generally not possible from unprivileged processes. The EPSS score is reported as less than 1%, and the vulnerability is not listed in CISA's KEV catalog, indicating a low likelihood of exploitation in the wild at present.