netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()_CVE-2026-23458

{
    "lastseen": "",
    "description": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()\n\nctnetlink_dump_exp_ct() stores a conntrack pointer in cb->data for the\nnetlink dump callback ctnetlink_exp_ct_dump_table(), but drops the\nconntrack reference immediately after netlink_dump_start().  When the\ndump spans multiple rounds, the second recvmsg() triggers the dump\ncallback which dereferences the now-freed conntrack via nfct_help(ct),\nleading to a use-after-free on ct->ext.\n\nThe bug is that the netlink_dump_control has no .start or .done\ncallbacks to manage the conntrack reference across dump rounds.  Other\ndump functions in the same file (e.g. ctnetlink_get_conntrack) properly\nuse .start/.done callbacks for this purpose.\n\nFix this by adding .start and .done callbacks that hold and release the\nconntrack reference for the duration of the dump, and move the\nnfct_help() call after the cb->args[0] early-return check in the dump\ncallback to avoid dereferencing ct->ext unnecessarily.\n\n BUG: KASAN: slab-use-after-free in ctnetlink_exp_ct_dump_table+0x4f/0x2e0\n Read of size 8 at addr ffff88810597ebf0 by task ctnetlink_poc/133\n\n CPU: 1 UID: 0 PID: 133 Comm: ctnetlink_poc Not tainted 7.0.0-rc2+ #3 PREEMPTLAZY\n Call Trace:\n  <TASK>\n  ctnetlink_exp_ct_dump_table+0x4f/0x2e0\n  netlink_dump+0x333/0x880\n  netlink_recvmsg+0x3e2/0x4b0\n  ? aa_sk_perm+0x184/0x450\n  sock_recvmsg+0xde/0xf0\n\n Allocated by task 133:\n  kmem_cache_alloc_noprof+0x134/0x440\n  __nf_conntrack_alloc+0xa8/0x2b0\n  ctnetlink_create_conntrack+0xa1/0x900\n  ctnetlink_new_conntrack+0x3cf/0x7d0\n  nfnetlink_rcv_msg+0x48e/0x510\n  netlink_rcv_skb+0xc9/0x1f0\n  nfnetlink_rcv+0xdb/0x220\n  netlink_unicast+0x3ec/0x590\n  netlink_sendmsg+0x397/0x690\n  __sys_sendmsg+0xf4/0x180\n\n Freed by task 0:\n  slab_free_after_rcu_debug+0xad/0x1e0\n  rcu_core+0x5c3/0x9c0",
    "published": "2026-04-03T15:15:39.041Z",
    "modified": "2026-04-27T14:02:36.862Z",
    "type": "cve",
    "title": "netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/d8cd0efbccc5cfb0a80da744a7da76e1333ab925\nhttps://git.kernel.org/stable/c/9821b47f669eb82791fa0b1a6ebaf9aa219bea72\nhttps://git.kernel.org/stable/c/bdf2724eefd4455a66863abb025bab8d3aa98c57\nhttps://git.kernel.org/stable/c/f04cc86d59906513d2d62183b882966fc0ae0390\nhttps://git.kernel.org/stable/c/f025171feef2ac65663d7986f1d5ff0c28d6b2a9\nhttps://git.kernel.org/stable/c/04c8907ce4e3d3e26c5e1a3e47aa5d17082cbb56\nhttps://git.kernel.org/stable/c/cd541f15b60e2257441398cf495d978f816d09f8\nhttps://git.kernel.org/stable/c/5cb81eeda909dbb2def209dd10636b51549a3f8a",
    "id": "CVE-2026-23458",
    "bulletinFamily": "",
    "cwe": null,
    "cvelist": null,
    "sourceData": "Linux Linux e844a928431fa8f1359d1f4f2cef53d9b446bf52\nLinux Linux e844a928431fa8f1359d1f4f2cef53d9b446bf52\nLinux Linux e844a928431fa8f1359d1f4f2cef53d9b446bf52\nLinux Linux e844a928431fa8f1359d1f4f2cef53d9b446bf52\nLinux Linux e844a928431fa8f1359d1f4f2cef53d9b446bf52\nLinux Linux e844a928431fa8f1359d1f4f2cef53d9b446bf52\nLinux Linux e844a928431fa8f1359d1f4f2cef53d9b446bf52\nLinux Linux e844a928431fa8f1359d1f4f2cef53d9b446bf52\nLinux Linux 3.10",
    "sourceHref": "",
    "cvss": {
        "score": 7.8,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
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            "privilegesRequired": "",
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            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Linux",
    "version": "e844a928431fa8f1359d1f4f2cef53d9b446bf52",
    "vendor": "Linux",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}