{"id":"CVE-2026-98303","state":"PUBLISHED","title":"ipv4: icmp: reject RTN_UNREACHABLE input routes in icmp_route_lookup","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.","publishedAt":"2026-10-06T08:46:00.524Z","updatedAt":"2026-10-19T09:17:14.136Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8b7817f3a959ed99d7443afc12f78a7e1fcc2063","status":"affected","lessThan":"06083cea4a3b95f5ebc85312f97d7086e6c9e782","versionType":"git"},{"version":"8b7817f3a959ed99d7443afc12f78a7e1fcc2063","status":"affected","lessThan":"83aa83f81a8fec30ff5372dee60b2f0561bcb2ca","versionType":"git"},{"version":"8b7817f3a959ed99d7443afc12f78a7e1fcc2063","status":"affected","lessThan":"cac69c50716c712ef0114837c9427da66066124c","versionType":"git"},{"version":"8b7817f3a959ed99d7443afc12f78a7e1fcc2063","status":"affected","lessThan":"1af2d87964d87ba7626d96928d68c09158b5a223","versionType":"git"},{"version":"8b7817f3a959ed99d7443afc12f78a7e1fcc2063","status":"affected","lessThan":"fda3000147dc96c75ba162f680bec0a9fecf3037","versionType":"git"},{"version":"8b7817f3a959ed99d7443afc12f78a7e1fcc2063","status":"affected","lessThan":"2998147b59c9df0a51477c7a6b3d1f0ba3127dd4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/icmp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.25","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.25","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.54","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.8","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/icmp.c"]}],"references":["https://git.kernel.org/stable/c/06083cea4a3b95f5ebc85312f97d7086e6c9e782","https://git.kernel.org/stable/c/83aa83f81a8fec30ff5372dee60b2f0561bcb2ca","https://git.kernel.org/stable/c/cac69c50716c712ef0114837c9427da66066124c","https://git.kernel.org/stable/c/1af2d87964d87ba7626d96928d68c09158b5a223","https://git.kernel.org/stable/c/fda3000147dc96c75ba162f680bec0a9fecf3037","https://git.kernel.org/stable/c/2998147b59c9df0a51477c7a6b3d1f0ba3127dd4"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98303.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98303","state":"PUBLISHED","datePublished":"2026-10-06T08:46:00.524Z","dateUpdated":"2026-10-19T09:17:14.136Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.338Z"},"containers":{"cna":{"title":"ipv4: icmp: reject RTN_UNREACHABLE input routes in icmp_route_lookup","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8b7817f3a959ed99d7443afc12f78a7e1fcc2063","status":"affected","lessThan":"06083cea4a3b95f5ebc85312f97d7086e6c9e782","versionType":"git"},{"version":"8b7817f3a959ed99d7443afc12f78a7e1fcc2063","status":"affected","lessThan":"83aa83f81a8fec30ff5372dee60b2f0561bcb2ca","versionType":"git"},{"version":"8b7817f3a959ed99d7443afc12f78a7e1fcc2063","status":"affected","lessThan":"cac69c50716c712ef0114837c9427da66066124c","versionType":"git"},{"version":"8b7817f3a959ed99d7443afc12f78a7e1fcc2063","status":"affected","lessThan":"1af2d87964d87ba7626d96928d68c09158b5a223","versionType":"git"},{"version":"8b7817f3a959ed99d7443afc12f78a7e1fcc2063","status":"affected","lessThan":"fda3000147dc96c75ba162f680bec0a9fecf3037","versionType":"git"},{"version":"8b7817f3a959ed99d7443afc12f78a7e1fcc2063","status":"affected","lessThan":"2998147b59c9df0a51477c7a6b3d1f0ba3127dd4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/icmp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.25","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.25","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.54","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.8","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/icmp.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/06083cea4a3b95f5ebc85312f97d7086e6c9e782"},{"url":"https://git.kernel.org/stable/c/83aa83f81a8fec30ff5372dee60b2f0561bcb2ca"},{"url":"https://git.kernel.org/stable/c/cac69c50716c712ef0114837c9427da66066124c"},{"url":"https://git.kernel.org/stable/c/1af2d87964d87ba7626d96928d68c09158b5a223"},{"url":"https://git.kernel.org/stable/c/fda3000147dc96c75ba162f680bec0a9fecf3037"},{"url":"https://git.kernel.org/stable/c/2998147b59c9df0a51477c7a6b3d1f0ba3127dd4"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:17:14.136Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"6.12.112"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"6.18.54"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"7.2.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}