{"api_version":"1","generated_at":"2026-05-13T07:41:51+00:00","cve":"CVE-2026-31531","urls":{"html":"https://cve.report/CVE-2026-31531","api":"https://cve.report/api/cve/CVE-2026-31531.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-31531","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-31531"},"summary":{"title":"ipv4: nexthop: allocate skb dynamically in rtm_get_nexthop()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: nexthop: allocate skb dynamically in rtm_get_nexthop()\n\nWhen querying a nexthop object via RTM_GETNEXTHOP, the kernel currently\nallocates a fixed-size skb using NLMSG_GOODSIZE. While sufficient for\nsingle nexthops and small Equal-Cost Multi-Path groups, this fixed\nallocation fails for large nexthop groups like 512 nexthops.\n\nThis results in the following warning splat:\n\n WARNING: net/ipv4/nexthop.c:3395 at rtm_get_nexthop+0x176/0x1c0, CPU#20: rep/4608\n [...]\n RIP: 0010:rtm_get_nexthop (net/ipv4/nexthop.c:3395)\n [...]\n Call Trace:\n  <TASK>\n  rtnetlink_rcv_msg (net/core/rtnetlink.c:6989)\n  netlink_rcv_skb (net/netlink/af_netlink.c:2550)\n  netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344)\n  netlink_sendmsg (net/netlink/af_netlink.c:1894)\n  ____sys_sendmsg (net/socket.c:721 net/socket.c:736 net/socket.c:2585)\n  ___sys_sendmsg (net/socket.c:2641)\n  __sys_sendmsg (net/socket.c:2671)\n  do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)\n  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)\n  </TASK>\n\nFix this by allocating the size dynamically using nh_nlmsg_size() and\nusing nlmsg_new(), this is consistent with nexthop_notify() behavior. In\naddition, adjust nh_nlmsg_size_grp() so it calculates the size needed\nbased on flags passed. While at it, also add the size of NHA_FDB for\nnexthop group size calculation as it was missing too.\n\nThis cannot be reproduced via iproute2 as the group size is currently\nlimited and the command fails as follows:\n\naddattr_l ERROR: message exceeded bound of 1048","state":"PUBLISHED","assigner":"Linux","published_at":"2026-04-23 12:17:01","updated_at":"2026-04-28 17:38:49"},"problem_types":["NVD-CWE-noinfo"],"metrics":[{"version":"3.1","source":"nvd@nist.gov","type":"Primary","score":"5.5","severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"}}],"references":[{"url":"https://git.kernel.org/stable/c/615517f3f8d53b0cf41507c7599971e17adfdfa5","name":"https://git.kernel.org/stable/c/615517f3f8d53b0cf41507c7599971e17adfdfa5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/635038fe19db391117e66b46bdc2b6e447ac801d","name":"https://git.kernel.org/stable/c/635038fe19db391117e66b46bdc2b6e447ac801d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/40bd39e383a0478fd5c221f393df05fd9d70cfbc","name":"https://git.kernel.org/stable/c/40bd39e383a0478fd5c221f393df05fd9d70cfbc","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/14cf0cd35361f4e94824bf8a42f72713d7702a73","name":"https://git.kernel.org/stable/c/14cf0cd35361f4e94824bf8a42f72713d7702a73","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-31531","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31531","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 430a049190de3c9e219f43084de9f1122da04570 615517f3f8d53b0cf41507c7599971e17adfdfa5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 430a049190de3c9e219f43084de9f1122da04570 40bd39e383a0478fd5c221f393df05fd9d70cfbc git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 430a049190de3c9e219f43084de9f1122da04570 635038fe19db391117e66b46bdc2b6e447ac801d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 430a049190de3c9e219f43084de9f1122da04570 14cf0cd35361f4e94824bf8a42f72713d7702a73 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.3","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.3 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.83 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.24 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19.14 6.19.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[{"cve_year":"2026","cve_id":"31531","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"linux","cpe5":"linux_kernel","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"}],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"31531","cve":"CVE-2026-31531","epss":"0.000100000","percentile":"0.011770000","score_date":"2026-04-26","updated_at":"2026-04-27 00:09:42"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/ipv4/nexthop.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"615517f3f8d53b0cf41507c7599971e17adfdfa5","status":"affected","version":"430a049190de3c9e219f43084de9f1122da04570","versionType":"git"},{"lessThan":"40bd39e383a0478fd5c221f393df05fd9d70cfbc","status":"affected","version":"430a049190de3c9e219f43084de9f1122da04570","versionType":"git"},{"lessThan":"635038fe19db391117e66b46bdc2b6e447ac801d","status":"affected","version":"430a049190de3c9e219f43084de9f1122da04570","versionType":"git"},{"lessThan":"14cf0cd35361f4e94824bf8a42f72713d7702a73","status":"affected","version":"430a049190de3c9e219f43084de9f1122da04570","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/ipv4/nexthop.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.3"},{"lessThan":"5.3","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.83","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.24","versionType":"semver"},{"lessThanOrEqual":"6.19.*","status":"unaffected","version":"6.19.14","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.0","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.83","versionStartIncluding":"5.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.24","versionStartIncluding":"5.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.19.14","versionStartIncluding":"5.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0","versionStartIncluding":"5.3","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: nexthop: allocate skb dynamically in rtm_get_nexthop()\n\nWhen querying a nexthop object via RTM_GETNEXTHOP, the kernel currently\nallocates a fixed-size skb using NLMSG_GOODSIZE. While sufficient for\nsingle nexthops and small Equal-Cost Multi-Path groups, this fixed\nallocation fails for large nexthop groups like 512 nexthops.\n\nThis results in the following warning splat:\n\n WARNING: net/ipv4/nexthop.c:3395 at rtm_get_nexthop+0x176/0x1c0, CPU#20: rep/4608\n [...]\n RIP: 0010:rtm_get_nexthop (net/ipv4/nexthop.c:3395)\n [...]\n Call Trace:\n  <TASK>\n  rtnetlink_rcv_msg (net/core/rtnetlink.c:6989)\n  netlink_rcv_skb (net/netlink/af_netlink.c:2550)\n  netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344)\n  netlink_sendmsg (net/netlink/af_netlink.c:1894)\n  ____sys_sendmsg (net/socket.c:721 net/socket.c:736 net/socket.c:2585)\n  ___sys_sendmsg (net/socket.c:2641)\n  __sys_sendmsg (net/socket.c:2671)\n  do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)\n  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)\n  </TASK>\n\nFix this by allocating the size dynamically using nh_nlmsg_size() and\nusing nlmsg_new(), this is consistent with nexthop_notify() behavior. In\naddition, adjust nh_nlmsg_size_grp() so it calculates the size needed\nbased on flags passed. While at it, also add the size of NHA_FDB for\nnexthop group size calculation as it was missing too.\n\nThis cannot be reproduced via iproute2 as the group size is currently\nlimited and the command fails as follows:\n\naddattr_l ERROR: message exceeded bound of 1048"}],"providerMetadata":{"dateUpdated":"2026-04-23T11:12:44.143Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/615517f3f8d53b0cf41507c7599971e17adfdfa5"},{"url":"https://git.kernel.org/stable/c/40bd39e383a0478fd5c221f393df05fd9d70cfbc"},{"url":"https://git.kernel.org/stable/c/635038fe19db391117e66b46bdc2b6e447ac801d"},{"url":"https://git.kernel.org/stable/c/14cf0cd35361f4e94824bf8a42f72713d7702a73"}],"title":"ipv4: nexthop: allocate skb dynamically in rtm_get_nexthop()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-31531","datePublished":"2026-04-23T11:12:44.143Z","dateReserved":"2026-03-09T15:48:24.112Z","dateUpdated":"2026-04-23T11:12:44.143Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-04-23 12:17:01","lastModifiedDate":"2026-04-28 17:38:49","problem_types":["NVD-CWE-noinfo"],"metrics":{"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":3.6}]},"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"6.12.83","matchCriteriaId":"A776C96C-AD0E-490C-AE7A-9FB2F402EB0D"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"6.18.24","matchCriteriaId":"8126B8B8-6D0B-4443-86C1-672AEE893555"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19","versionEndExcluding":"6.19.14","matchCriteriaId":"D6A8A074-BBF4-4803-ABED-519A839435BB"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*","matchCriteriaId":"F253B622-8837-4245-BCE5-A7BF8FC76A16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*","matchCriteriaId":"4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*","matchCriteriaId":"F666C8D8-6538-46D4-B318-87610DE64C34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*","matchCriteriaId":"02259FDA-961B-47BC-AE7F-93D7EC6E90C2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*","matchCriteriaId":"58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*","matchCriteriaId":"1D2315C0-D46F-4F85-9754-F9E5E11374A6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*","matchCriteriaId":"512EE3A8-A590-4501-9A94-5D4B268D6138"}]}]}]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"31531","Ordinal":"1","Title":"ipv4: nexthop: allocate skb dynamically in rtm_get_nexthop()","CVE":"CVE-2026-31531","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"31531","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: nexthop: allocate skb dynamically in rtm_get_nexthop()\n\nWhen querying a nexthop object via RTM_GETNEXTHOP, the kernel currently\nallocates a fixed-size skb using NLMSG_GOODSIZE. While sufficient for\nsingle nexthops and small Equal-Cost Multi-Path groups, this fixed\nallocation fails for large nexthop groups like 512 nexthops.\n\nThis results in the following warning splat:\n\n WARNING: net/ipv4/nexthop.c:3395 at rtm_get_nexthop+0x176/0x1c0, CPU#20: rep/4608\n [...]\n RIP: 0010:rtm_get_nexthop (net/ipv4/nexthop.c:3395)\n [...]\n Call Trace:\n  <TASK>\n  rtnetlink_rcv_msg (net/core/rtnetlink.c:6989)\n  netlink_rcv_skb (net/netlink/af_netlink.c:2550)\n  netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344)\n  netlink_sendmsg (net/netlink/af_netlink.c:1894)\n  ____sys_sendmsg (net/socket.c:721 net/socket.c:736 net/socket.c:2585)\n  ___sys_sendmsg (net/socket.c:2641)\n  __sys_sendmsg (net/socket.c:2671)\n  do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)\n  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)\n  </TASK>\n\nFix this by allocating the size dynamically using nh_nlmsg_size() and\nusing nlmsg_new(), this is consistent with nexthop_notify() behavior. In\naddition, adjust nh_nlmsg_size_grp() so it calculates the size needed\nbased on flags passed. While at it, also add the size of NHA_FDB for\nnexthop group size calculation as it was missing too.\n\nThis cannot be reproduced via iproute2 as the group size is currently\nlimited and the command fails as follows:\n\naddattr_l ERROR: message exceeded bound of 1048","Type":"Description","Title":"ipv4: nexthop: allocate skb dynamically in rtm_get_nexthop()"}]}}}