{
  "threat_severity" : "Moderate",
  "public_date" : "2026-03-25T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: netfilter: nft_set_pipapo: split gc into unlink and reclaim phase",
    "id" : "2451254",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2451254"
  },
  "cvss3" : {
    "cvss3_base_score" : "5.5",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
    "status" : "draft"
  },
  "cwe" : "CWE-825",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nnetfilter: nft_set_pipapo: split gc into unlink and reclaim phase\nYiming Qian reports Use-after-free in the pipapo set type:\nUnder a large number of expired elements, commit-time GC can run for a very\nlong time in a non-preemptible context, triggering soft lockup warnings and\nRCU stall reports (local denial of service).\nWe must split GC in an unlink and a reclaim phase.\nWe cannot queue elements for freeing until pointers have been swapped.\nExpired elements are still exposed to both the packet path and userspace\ndumpers via the live copy of the data structure.\ncall_rcu() does not protect us: dump operations or element lookups starting\nafter call_rcu has fired can still observe the free'd element, unless the\ncommit phase has made enough progress to swap the clone and live pointers\nbefore any new reader has picked up the old version.\nThis a similar approach as done recently for the rbtree backend in commit\n35f83a75529a (\"netfilter: nft_set_rbtree: don't gc elements on insert\").", "A flaw was found in the Linux kernel's netfilter component, specifically within the `nft_set_pipapo` module. A local attacker could exploit a use-after-free vulnerability when a large number of expired elements are present. This can cause the garbage collection (GC) process to run for an extended period in a non-preemptible context, leading to soft lockup warnings and RCU (Read-Copy-Update) stall reports, resulting in a local denial of service." ],
  "statement" : "This flaw affects nftables firewall configurations using pipapo sets (e.g., for IP range matching). When many elements expire simultaneously, GC can cause soft lockups and RCU stalls. The UAF occurs because freed elements remain visible to packet path and dump operations during the clone/live pointer swap window.",
  "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" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "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-2026-23351\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-23351\nhttps://lore.kernel.org/linux-cve-announce/2026032536-CVE-2026-23351-637f@gregkh/T" ],
  "name" : "CVE-2026-23351",
  "csaw" : false
}