{"affected":[{"defaultStatus":"unaffected","product":"Linux","source":"CNA: Linux","vendor":"Linux","versions":[{"lessThan":"5f479aac1262959e54cdd978d873be5f202e2a40","status":"affected","version":"430a049190de3c9e219f43084de9f1122da04570","versionType":"git"},{"lessThan":"18a4543c1750f96be63e349936d2dfdcb360b2dc","status":"affected","version":"430a049190de3c9e219f43084de9f1122da04570","versionType":"git"},{"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","source":"CNA: Linux","vendor":"Linux","versions":[{"status":"affected","version":"5.3"},{"lessThan":"5.3","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.191","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.160","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"}]}],"cveId":"CVE-2026-31531","cwes":[],"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","epss":{"date":"2026-11-05","percentile":0.0574,"score":0.00165},"exploits":[],"kev":null,"metrics":[],"modifiedAt":1793915106641,"publishedAt":1776942764143,"references":[{"source":"CNA: Linux","tags":[],"url":"https://git.kernel.org/stable/c/5f479aac1262959e54cdd978d873be5f202e2a40"},{"source":"CNA: Linux","tags":[],"url":"https://git.kernel.org/stable/c/18a4543c1750f96be63e349936d2dfdcb360b2dc"},{"source":"CNA: Linux","tags":[],"url":"https://git.kernel.org/stable/c/615517f3f8d53b0cf41507c7599971e17adfdfa5"},{"source":"CNA: Linux","tags":[],"url":"https://git.kernel.org/stable/c/40bd39e383a0478fd5c221f393df05fd9d70cfbc"},{"source":"CNA: Linux","tags":[],"url":"https://git.kernel.org/stable/c/635038fe19db391117e66b46bdc2b6e447ac801d"},{"source":"CNA: Linux","tags":[],"url":"https://git.kernel.org/stable/c/14cf0cd35361f4e94824bf8a42f72713d7702a73"}],"remediation":[],"revision":"b1ed9ddcb8e4612da1f18a7b2af5d7771358051a7a3f0e2a32b1808f0a05478b","sources":[{"modifiedAt":1793915106641,"name":"CNA: Linux","retrievedAt":1793917088315,"url":"https://www.cve.org/CVERecord?id=CVE-2026-31531"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1793917102657,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-31531"}],"ssvc":{"assessedAt":1793914673479,"automatable":"no","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"partial"},"status":"published","title":"ipv4: nexthop: allocate skb dynamically in rtm_get_nexthop()","updatedAt":1793917102657}