{
  "threat_severity" : "Low",
  "public_date" : "2025-03-12T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: bpf: Fix softlockup in arena_map_free on 64k page kernel",
    "id" : "2351606",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2351606"
  },
  "cvss3" : {
    "cvss3_base_score" : "2.3",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L",
    "status" : "verified"
  },
  "cwe" : "CWE-667",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nbpf: Fix softlockup in arena_map_free on 64k page kernel\nOn an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y,\narena_htab tests cause a segmentation fault and soft lockup.\nThe same failure is not observed with 4k pages on aarch64.\nIt turns out arena_map_free() is calling\napply_to_existing_page_range() with the address returned by\nbpf_arena_get_kern_vm_start().  If this address is not page-aligned\nthe code ends up calling apply_to_pte_range() with that unaligned\naddress causing soft lockup.\nFix it by round up GUARD_SZ to PAGE_SIZE << 1 so that the\ndivision by 2 in bpf_arena_get_kern_vm_start() returns\na page-aligned value." ],
  "statement" : "The default Red Hat Enterprise Linux kernel prevents unprivileged users from being able to use eBPF by the kernel.unprivileged_bpf_disabled sysctl. This would require a privileged user with CAP_SYS_ADMIN or root to be able to abuse this flaw reducing its attack space.\nFor the Red Hat Enterprise Linux 9 to confirm the current state, inspect the sysctl with the command:\ncat /proc/sys/kernel/unprivileged_bpf_disabled\nThe setting of 1 would mean that unprivileged users can not use eBPF, mitigating the flaw.",
  "affected_release" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "release_date" : "2025-11-11T00:00:00Z",
    "advisory" : "RHSA-2025:20095",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10.1",
    "package" : "kernel-0:6.12.0-124.8.1.el10_1"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2025-11-11T00:00:00Z",
    "advisory" : "RHSA-2025:20518",
    "cpe" : "cpe:/a:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-611.5.1.el9_7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2025-11-11T00:00:00Z",
    "advisory" : "RHSA-2025:20518",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-611.5.1.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" : "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" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Not affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "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-2025-21851\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-21851\nhttps://lore.kernel.org/linux-cve-announce/2025031213-CVE-2025-21851-87bd@gregkh/T" ],
  "name" : "CVE-2025-21851",
  "csaw" : false
}