{
  "threat_severity" : "Low",
  "public_date" : "2026-04-03T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()",
    "id" : "2454816",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2454816"
  },
  "cvss3" : {
    "cvss3_base_score" : "4.4",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H",
    "status" : "draft"
  },
  "cwe" : "CWE-911",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nnetfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()\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.\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.\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.\nBUG: KASAN: slab-use-after-free in ctnetlink_exp_ct_dump_table+0x4f/0x2e0\nRead of size 8 at addr ffff88810597ebf0 by task ctnetlink_poc/133\nCPU: 1 UID: 0 PID: 133 Comm: ctnetlink_poc Not tainted 7.0.0-rc2+ #3 PREEMPTLAZY\nCall Trace:\n<TASK>\nctnetlink_exp_ct_dump_table+0x4f/0x2e0\nnetlink_dump+0x333/0x880\nnetlink_recvmsg+0x3e2/0x4b0\n? aa_sk_perm+0x184/0x450\nsock_recvmsg+0xde/0xf0\nAllocated by task 133:\nkmem_cache_alloc_noprof+0x134/0x440\n__nf_conntrack_alloc+0xa8/0x2b0\nctnetlink_create_conntrack+0xa1/0x900\nctnetlink_new_conntrack+0x3cf/0x7d0\nnfnetlink_rcv_msg+0x48e/0x510\nnetlink_rcv_skb+0xc9/0x1f0\nnfnetlink_rcv+0xdb/0x220\nnetlink_unicast+0x3ec/0x590\nnetlink_sendmsg+0x397/0x690\n__sys_sendmsg+0xf4/0x180\nFreed by task 0:\nslab_free_after_rcu_debug+0xad/0x1e0\nrcu_core+0x5c3/0x9c0", "A flaw was found in the Linux kernel's netfilter connection tracking (ctnetlink) component. This vulnerability, known as a use-after-free, occurs when the system attempts to access a memory location after it has been deallocated, which can lead to unpredictable behavior. A local attacker could exploit this by triggering a specific sequence of network communication operations (netlink dump callbacks) related to connection tracking. This could result in a denial of service, causing system instability or crashes." ],
  "statement" : "The conntrack pointer was stored in dump callback state without holding a reference across multi-recvmsg dump rounds. Exploitation requires ability to use ctnetlink (typically CAP_NET_ADMIN). The fix uses .start/.done callbacks to pin the reference for the dump lifetime.",
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10"
  }, {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Out of support scope",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2026-23458\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-23458\nhttps://lore.kernel.org/linux-cve-announce/2026040318-CVE-2026-23458-5578@gregkh/T" ],
  "name" : "CVE-2026-23458",
  "csaw" : false
}