{"id":"CVE-2026-98239","published":"2026-10-06T09:18:11.803","lastModified":"2026-10-07T07:17:05.810","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: lan743x: fix RX checksum use-after-free\n\nlan743x_rx_process_buffer() adds each non-first receive buffer to the\nhead skb's frag_list.  On the last descriptor, lan743x_rx_trim_skb()\nlinearizes the head and frees the fragment skb metadata.\n\nThe checksum-success path then writes ip_summed through the local skb\npointer, which still points to the final fragment.  This causes a\nuse-after-free write when a packet spans more than one receive buffer.\n\nSet ip_summed on the surviving head skb instead.  Multi-buffer receive\ncan occur after a live MTU increase because existing ring entries keep\ntheir old buffer size until they are replenished.\n\nA KUnit test invoking lan743x_rx_process_buffer() with a two-buffer\npacket produced a one-byte KASAN use-after-free write before this change.\nThe same test passed after the change.  The driver object also builds\nwith W=1.  This was not tested on physical LAN743x hardware.","cvssScore":8.1,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/0e52886c4324c9897c2c62f92be3dc8316cee67e","tags":[]},{"url":"https://git.kernel.org/stable/c/161a403c8625e152de03d1da22bbf9cda6dc9f9f","tags":[]},{"url":"https://git.kernel.org/stable/c/5c216bfa9fb7b36804485e67975e9c98055b31ef","tags":[]},{"url":"https://git.kernel.org/stable/c/6fe5c3a2503983abb431d93faeadfc7f5e6a7e33","tags":[]},{"url":"https://git.kernel.org/stable/c/a58024835c704419bb46d2a34e5223f65605f958","tags":[]},{"url":"https://git.kernel.org/stable/c/a9ce4053dc945c5372dedba5017ee675b30dc0c5","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":{"summary":"The Linux kernel's LAN743x network driver has a use-after-free vulnerability in its RX checksum processing logic. When packets span multiple receive buffers, the driver incorrectly writes to freed fragment skb metadata instead of the surviving head skb, potentially leading to memory corruption.","exploitability":"Exploitation is moderately difficult as it requires specific conditions including multi-buffer packet reception and a live MTU increase, but could be triggered through network traffic patterns that cause the affected driver to process fragmented packets.","blast_radius":"The vulnerability could affect systems running Linux with LAN743x network adapters, potentially leading to kernel memory corruption that might result in system instability or denial of service, though remote code execution is not directly indicated.","remediation":"Apply the kernel patch that fixes the lan743x_rx_process_buffer() function to correctly set ip_summed on the surviving head skb instead of the freed fragment.","detection":"No reliable host or network indicator is derivable from the published description.","tags":["network","kernel","memory-corruption","lan743x"],"model":"garnet-coder","analyzedAt":"2026-10-14T08:59:13.705Z"}}