CVE-2026-99127 is a Linux kernel vulnerability involving misalignment of fragment offsets in the page pool allocator for odd-sized requests. This misalignment can cause kernel panics due to split lock detection on x86 architectures when cloning socket buffers. The issue affects the per-CPU system_page_pool used by generic XDP and can be triggered by attaching an XDP program to loopback and opening a RAW IPPROTO_UDP socket. The vulnerability has been resolved by ensuring fragment sizes are aligned to the required DMA cache alignment, preventing misaligned fragment offsets and subsequent kernel panics.