{"id":"CVE-2026-98303","summary":"ipv4: icmp: reject RTN_UNREACHABLE input routes in icmp_route_lookup","details":"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.","modified":"2026-10-08T02:50:03.826986831Z","published":"2026-10-06T08:46:00.524Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98303.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/06083cea4a3b95f5ebc85312f97d7086e6c9e782"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1af2d87964d87ba7626d96928d68c09158b5a223"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2998147b59c9df0a51477c7a6b3d1f0ba3127dd4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/83aa83f81a8fec30ff5372dee60b2f0561bcb2ca"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cac69c50716c712ef0114837c9427da66066124c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fda3000147dc96c75ba162f680bec0a9fecf3037"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98303.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98303"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"8b7817f3a959ed99d7443afc12f78a7e1fcc2063"},{"fixed":"06083cea4a3b95f5ebc85312f97d7086e6c9e782"},{"fixed":"83aa83f81a8fec30ff5372dee60b2f0561bcb2ca"},{"fixed":"cac69c50716c712ef0114837c9427da66066124c"},{"fixed":"1af2d87964d87ba7626d96928d68c09158b5a223"},{"fixed":"fda3000147dc96c75ba162f680bec0a9fecf3037"},{"fixed":"2998147b59c9df0a51477c7a6b3d1f0ba3127dd4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98303.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.25"},{"fixed":"6.1.189"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.158"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.112"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.54"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.8"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98303.json"}}],"schema_version":"1.9.0"}