{"id":"CVE-2026-98303","published":"2026-10-06T09:18:21.370","lastModified":"2026-10-06T09:18:21.370","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: icmp: reject RTN_UNREACHABLE input routes in icmp_route_lookup\n\nWhen the forward output route cannot be used in icmp_route_lookup(),\nit enters the \"reverse path\" and calls ip_route_input() on fl4_dec.daddr,\nthe original packet's source address.\n\nip_route_input() only returns an error for truly invalid packets. For\nunreachable addresses it will succeed and return an input route whose\ndst.output is set to ip_rt_bug(). The existing check only rejects\nRTN_LOCAL routes, so the RTN_UNREACHABLE route types can still be returned\nand later used for output, syzkaller triggering a WARN_ON_ONCE()\nin ip_rt_bug() as bellow:\n\n ------------[ cut here ]------------\n WARNING: net/ipv4/route.c:1273 at ip_rt_bug+0x14/0x20\n RIP: 0010:ip_rt_bug+0x14/0x20\n Call Trace:\n  ip_push_pending_frames+0xfa/0x100\n  __icmp_send+0x905/0xf10\n  ip_options_compile+0xc0/0xd0\n  ip_rcv_finish_core+0x321/0xae0\n  ip_rcv+0x1de/0x260\n  __netif_receive_skb_one_core+0x11a/0x130\n  netif_receive_skb+0x7b/0x260\n  tun_get_user+0x11bf/0x1c10\n ------------[ cut here ]------------\n\nReject input route that is RTN_UNREACHABLE to fix it. The net warning\nis only printed for RTN_LOCAL, as RTN_UNREACHABLE is not the result of\na race condition.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/06083cea4a3b95f5ebc85312f97d7086e6c9e782","tags":[]},{"url":"https://git.kernel.org/stable/c/1af2d87964d87ba7626d96928d68c09158b5a223","tags":[]},{"url":"https://git.kernel.org/stable/c/2998147b59c9df0a51477c7a6b3d1f0ba3127dd4","tags":[]},{"url":"https://git.kernel.org/stable/c/83aa83f81a8fec30ff5372dee60b2f0561bcb2ca","tags":[]},{"url":"https://git.kernel.org/stable/c/cac69c50716c712ef0114837c9427da66066124c","tags":[]},{"url":"https://git.kernel.org/stable/c/fda3000147dc96c75ba162f680bec0a9fecf3037","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}