CVE-2025-38622: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-38622 is a vulnerability discovered in the Linux kernel affecting the UDP packet handling mechanism. The issue was disclosed on August 22, 2025, and involves the net subsystem's handling of UFO (UDP Fragmentation Offload) packets in the udp_rcv_segment() function (NVD).

The vulnerability occurs when sending a packet with virtio_net_hdr to a tun device. If the gso_type in virtio_net_hdr is SKB_GSO_UDP and the gso_size is less than udphdr size, it can trigger a kernel crash. The issue stems from the segmentation in UDP receive path that was introduced by commit cf329aa42b66 ("udp: cope with UDP GRO packet misdirection") which was intended only for GRO but not UFO packets (NVD).

When exploited, this vulnerability can cause a kernel crash, leading to a denial of service condition. The crash occurs in the net/core/skbuff.c file at line 4572, triggering a kernel BUG with an invalid opcode (NVD).

The vulnerability has been resolved by implementing a fix to drop UFO packets in udp_rcv_segment(). This solution prevents the crash by ensuring that UFO packets are not processed in a way that could trigger the vulnerability (NVD).