{
  "threat_severity" : "Moderate",
  "public_date" : "2026-03-04T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: kernel: Privilege escalation or denial of service via use-after-free in nf_tables_addchain()",
    "id" : "2444376",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2444376"
  },
  "cvss3" : {
    "cvss3_base_score" : "7.5",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
    "status" : "verified"
  },
  "cwe" : "CWE-416",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nnetfilter: nf_tables: fix use-after-free in nf_tables_addchain()\nnf_tables_addchain() publishes the chain to table->chains via\nlist_add_tail_rcu() (in nft_chain_add()) before registering hooks.\nIf nf_tables_register_hook() then fails, the error path calls\nnft_chain_del() (list_del_rcu()) followed by nf_tables_chain_destroy()\nwith no RCU grace period in between.\nThis creates two use-after-free conditions:\n1) Control-plane: nf_tables_dump_chains() traverses table->chains\nunder rcu_read_lock(). A concurrent dump can still be walking\nthe chain when the error path frees it.\n2) Packet path: for NFPROTO_INET, nf_register_net_hook() briefly\ninstalls the IPv4 hook before IPv6 registration fails.  Packets\nentering nft_do_chain() via the transient IPv4 hook can still be\ndereferencing chain->blob_gen_X when the error path frees the\nchain.\nAdd synchronize_rcu() between nft_chain_del() and the chain destroy\nso that all RCU readers -- both dump threads and in-flight packet\nevaluation -- have finished before the chain is freed.", "A flaw was found in the Linux kernel. A local attacker with CAP_NET_ADMIN capabilities, or remote packet traffic, could exploit a use-after-free vulnerability in the nf_tables_addchain() function's error handling. Successful exploitation could lead to a kernel crash, resulting in a Denial of Service (DoS), or potentially privilege escalation." ],
  "statement" : "A use after free can occur in nf_tables_addchain error handling because a new chain is published to table chains via RCU before hook registration completes and is then freed without an RCU grace period when hook registration fails. This creates a race with RCU readers in the control plane such as nf_tables_dump_chains and also with in flight packet evaluation when an IPv4 hook is transiently installed for NFPROTO_INET and later IPv6 hook registration fails. For the CVSS the PR is L because a local actor with CAP_NET_ADMIN can induce the failing add chain path while remote packet traffic may hit the transient hook and trigger the UAF window. Impact ranges from a kernel crash to potential privilege escalation.",
  "affected_release" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "release_date" : "2026-03-30T00:00:00Z",
    "advisory" : "RHSA-2026:6053",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10.1",
    "package" : "kernel-0:6.12.0-124.47.1.el10_1"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "release_date" : "2026-04-06T00:00:00Z",
    "advisory" : "RHSA-2026:6572",
    "cpe" : "cpe:/a:redhat:enterprise_linux:8::nfv",
    "package" : "kernel-rt-0:4.18.0-553.117.1.rt7.458.el8_10"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "release_date" : "2026-04-06T00:00:00Z",
    "advisory" : "RHSA-2026:6571",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8",
    "package" : "kernel-0:4.18.0-553.117.1.el8_10"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2026-04-06T00:00:00Z",
    "advisory" : "RHSA-2026:6570",
    "cpe" : "cpe:/a:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-611.47.1.el9_7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2026-04-06T00:00:00Z",
    "advisory" : "RHSA-2026:6570",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-611.47.1.el9_7"
  } ],
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2026-23231\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-23231\nhttps://lore.kernel.org/linux-cve-announce/2026030436-CVE-2026-23231-1a96@gregkh/T" ],
  "name" : "CVE-2026-23231",
  "mitigation" : {
    "value" : "In order to trigger the issue, it requires the ability to create user/net namespaces.\nOn non-containerized deployments of Red Hat Enterprise Linux 8, it is recommended to disable user namespaces by setting user.max_user_namespaces to 0:\n# echo \"user.max_user_namespaces=0\" > /etc/sysctl.d/userns.conf\n# sysctl -p /etc/sysctl.d/userns.conf\nOn containerized deployments, such as Red Hat OpenShift Container Platform, do not use this mitigation as the functionality is needed to be enabled.",
    "lang" : "en:us"
  },
  "csaw" : false
}