CVE-2026-31531

{"id": "CVE-2026-31531", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-31531", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-11-05T21:37:53.479222Z"}}], "cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 1.8}]}, "affected": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "affectedData": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "430a049190de3c9e219f43084de9f1122da04570", "lessThan": "5f479aac1262959e54cdd978d873be5f202e2a40", "versionType": "git"}, {"status": "affected", "version": "430a049190de3c9e219f43084de9f1122da04570", "lessThan": "18a4543c1750f96be63e349936d2dfdcb360b2dc", "versionType": "git"}, {"status": "affected", "version": "430a049190de3c9e219f43084de9f1122da04570", "lessThan": "615517f3f8d53b0cf41507c7599971e17adfdfa5", "versionType": "git"}, {"status": "affected", "version": "430a049190de3c9e219f43084de9f1122da04570", "lessThan": "40bd39e383a0478fd5c221f393df05fd9d70cfbc", "versionType": "git"}, {"status": "affected", "version": "430a049190de3c9e219f43084de9f1122da04570", "lessThan": "635038fe19db391117e66b46bdc2b6e447ac801d", "versionType": "git"}, {"status": "affected", "version": "430a049190de3c9e219f43084de9f1122da04570", "lessThan": "14cf0cd35361f4e94824bf8a42f72713d7702a73", "versionType": "git"}], "programFiles": ["net/ipv4/nexthop.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "5.3"}, {"status": "unaffected", "version": "0", "lessThan": "5.3", "versionType": "semver"}, {"status": "unaffected", "version": "6.1.191", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.160", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.83", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.18.24", "versionType": "semver", "lessThanOrEqual": "6.18.*"}, {"status": "unaffected", "version": "6.19.14", "versionType": "semver", "lessThanOrEqual": "6.19.*"}, {"status": "unaffected", "version": "7.0", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["net/ipv4/nexthop.c"], "defaultStatus": "affected"}]}], "published": "2026-04-23T12:17:01.820", "references": [{"url": "https://git.kernel.org/stable/c/14cf0cd35361f4e94824bf8a42f72713d7702a73", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/18a4543c1750f96be63e349936d2dfdcb360b2dc", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/40bd39e383a0478fd5c221f393df05fd9d70cfbc", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/5f479aac1262959e54cdd978d873be5f202e2a40", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/615517f3f8d53b0cf41507c7599971e17adfdfa5", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/635038fe19db391117e66b46bdc2b6e447ac801d", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "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"}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nipv4: nexthop: asignar skb din\u00e1micamente en rtm_get_nexthop()\n\nAl consultar un objeto nexthop a trav\u00e9s de RTM_GETNEXTHOP, el kernel actualmente\nasigna un skb de tama\u00f1o fijo usando NLMSG_GOODSIZE. Si bien es suficiente para\nnexthops individuales y grupos peque\u00f1os de rutas de costo igual (Equal-Cost Multi-Path), esta asignaci\u00f3n\nfija falla para grupos grandes de nexthops como 512 nexthops.\n\nEsto resulta en el siguiente \u2019warning splat\u2019:\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 Rastro de llamada:\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\nSolucione esto asignando el tama\u00f1o din\u00e1micamente usando nh_nlmsg_size() y\nusando nlmsg_new(), esto es consistente con el comportamiento de nexthop_notify(). Adem\u00e1s,\najuste nh_nlmsg_size_grp() para que calcule el tama\u00f1o necesario\nbasado en las banderas pasadas. Ya que estamos, tambi\u00e9n agregue el tama\u00f1o de NHA_FDB para\nel c\u00e1lculo del tama\u00f1o del grupo nexthop, ya que tambi\u00e9n faltaba.\n\nEsto no puede ser reproducido a trav\u00e9s de iproute2 ya que el tama\u00f1o del grupo est\u00e1 actualmente\nlimitado y el comando falla de la siguiente manera:\n\naddattr_l ERROR: el mensaje excedi\u00f3 el l\u00edmite de 1048"}], "lastModified": "2026-11-11T23:10:00.263", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "A776C96C-AD0E-490C-AE7A-9FB2F402EB0D", "versionEndExcluding": "6.12.83", "versionStartIncluding": "5.3"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "8126B8B8-6D0B-4443-86C1-672AEE893555", "versionEndExcluding": "6.18.24", "versionStartIncluding": "6.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "D6A8A074-BBF4-4803-ABED-519A839435BB", "versionEndExcluding": "6.19.14", "versionStartIncluding": "6.19"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}