Linux Distros Unpatched Vulnerability : CVE-2026-74612

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(338896);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/22");

  script_cve_id("CVE-2026-74612");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-74612");

  script_set_attribute(attribute:"synopsis", value:
"The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be
patched.");
  script_set_attribute(attribute:"description", value:
"The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied
patch available.

  - veth: fix skb length accounting after XDP frag adjustment veth exposes non-linear skb fragments through an
    xdp_buff. If an XDP program adjusts the fragment area, veth_xdp_rcv_skb() copies xdp_frags_size back to
    skb->data_len but leaves skb->len containing the old fragment contribution. After a fragment shrink, this
    makes skb_headlen() larger than the actual linear area. In the reproduced UDP receive path,
    __skb_datagram_iter() copied 1024 bytes past the actual linear tail to userspace, starting at struct
    skb_shared_info. The copied bytes included the affected skb's nr_frags, xdp_frags_size, and a kernel
    pointer from skb_shinfo(skb)->frags[0]. Real packet data was displaced by the same amount and truncated at
    the end. Subtract the old data_len before replacing it and add the new data_len afterwards, keeping
    skb->len and skb->data_len synchronized. Additionally, bpf_xdp_pull_data() can advance data_end while
    leaving frags present. The skb is then still non-linear, so the old __skb_put(skb, off) triggers
    SKB_LINEAR_ASSERT(). Use skb_set_tail_pointer() and update skb->len explicitly instead, following
    bpf_prog_run_generic_xdp(). Unlike __skb_put(), skb_set_tail_pointer() does not require a linear skb. A
    60000-byte UDP datagram on a veth pair with MTU 64000 was shortened by 1024 bytes from its fragment area.
    Before the fix, all 10 runs produced corrupted payloads. After the fix, all 10 runs matched the expected
    payload exactly. A forced-tailroom reproducer also exercises bpf_xdp_pull_data() with frags still present;
    the old code triggers SKB_LINEAR_ASSERT(), while this fix passes 10/10 runs. (CVE-2026-74612)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-74612");
  script_set_attribute(attribute:"solution", value:
"There is no known solution at this time.");
  script_set_attribute(attribute:"agent", value:"unix");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:U/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-74612");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_set_attribute(attribute:"vendor_unpatched", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/08/22");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/22");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:12.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:13.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:14.0");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:linux");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

  script_copyright(english:"This script is Copyright (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info2.nasl", "set_linux_os_id.nasl");
  script_require_keys("Host/cpu", "Host/local_checks_enabled", "global_settings/vendor_unpatched", "Host/OS/identifier");
  script_require_ports("Host/OS/Debian Linux-12", "Host/OS/Debian Linux-13", "Host/OS/Debian Linux-14");

  exit(0);
}

if (!get_kb_item("global_settings/vendor_unpatched")) exit(0, "Unpatched Vulnerabilities Detection not active.");
if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (empty_or_null(get_one_kb_item("Host/Debian/dpkg-l"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Debian Linux-12": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "12",
        "pkgs": [
          {"reference": "btrfs-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "cdrom-core-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "ext4-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "fat-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "isofs-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "jfs-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "kernel-image-6.1.0-50-alpha-generic-di"},
          {"reference": "linux-doc"},
          {"reference": "linux-doc-6.1"},
          {"reference": "linux-headers-6.1.0"},
          {"reference": "linux-source"},
          {"reference": "linux-source-6.1"},
          {"reference": "linux-support-6.1.0"},
          {"reference": "loop-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "nic-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "nic-shared-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "nic-wireless-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "pata-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "ppp-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "scsi-core-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "scsi-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "scsi-nic-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "serial-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "usb-serial-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "xfs-modules-6.1.0-50-alpha-generic-di"}
        ]
      }
    ]
  },
  "Debian Linux-14": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14",
        "pkgs": [
          {"reference": "bpftool"},
          {"reference": "hyperv-daemons"},
          {"reference": "intel-sdsi"},
          {"reference": "libcpupower-dev"},
          {"reference": "libcpupower1"},
          {"reference": "linux-base-7.1.8+deb14.1-alpha-generic"},
          {"reference": "linux-base-7.1.8+deb14.1-alpha-smp"},
          {"reference": "linux-base-7.1.8+deb14.1-amd64"},
          {"reference": "linux-base-7.1.8+deb14.1-arm64"},
          {"reference": "linux-base-7.1.8+deb14.1-arm64-16k"},
          {"reference": "linux-base-7.1.8+deb14.1-armmp"},
          {"reference": "linux-base-7.1.8+deb14.1-armmp-lpae"},
          {"reference": "linux-base-7.1.8+deb14.1-cloud-amd64"},
          {"reference": "linux-base-7.1.8+deb14.1-cloud-arm64"},
          {"reference": "linux-base-7.1.8+deb14.1-loong64"},
          {"reference": "linux-base-7.1.8+deb14.1-m68k"},
          {"reference": "linux-base-7.1.8+deb14.1-parisc"},
          {"reference": "linux-base-7.1.8+deb14.1-parisc64"},
          {"reference": "linux-base-7.1.8+deb14.1-powerpc"},
          {"reference": "linux-base-7.1.8+deb14.1-powerpc-smp"},
          {"reference": "linux-base-7.1.8+deb14.1-powerpc64"},
          {"reference": "linux-base-7.1.8+deb14.1-powerpc64-64k"},
          {"reference": "linux-base-7.1.8+deb14.1-powerpc64le"},
          {"reference": "linux-base-7.1.8+deb14.1-powerpc64le-64k"},
          {"reference": "linux-base-7.1.8+deb14.1-riscv64"},
          {"reference": "linux-base-7.1.8+deb14.1-rt-amd64"},
          {"reference": "linux-base-7.1.8+deb14.1-rt-arm64"},
          {"reference": "linux-base-7.1.8+deb14.1-s390x"},
          {"reference": "linux-base-7.1.8+deb14.1-sh7751r"},
          {"reference": "linux-base-7.1.8+deb14.1-sparc64"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "bpftool"},
          {"reference": "hyperv-daemons"},
          {"reference": "intel-sdsi"},
          {"reference": "libcpupower-dev"},
          {"reference": "libcpupower1"},
          {"reference": "linux-bpf-dev"},
          {"reference": "linux-config-6.12"},
          {"reference": "linux-cpupower"},
          {"reference": "linux-doc"},
          {"reference": "linux-doc-6.12"},
          {"reference": "linux-headers-4kc-malta"},
          {"reference": "linux-headers-5kc-malta"},
          {"reference": "linux-headers-6.12.94+deb13-4kc-malta"},
          {"reference": "linux-headers-6.12.94+deb13-5kc-malta"},
          {"reference": "linux-headers-6.12.94+deb13-alpha-generic"},
          {"reference": "linux-headers-6.12.94+deb13-alpha-smp"},
          {"reference": "linux-headers-6.12.94+deb13-amd64"},
          {"reference": "linux-headers-6.12.94+deb13-arm64"},
          {"reference": "linux-headers-6.12.94+deb13-arm64-16k"},
          {"reference": "linux-headers-6.12.94+deb13-armmp"},
          {"reference": "linux-headers-6.12.94+deb13-armmp-lpae"},
          {"reference": "linux-headers-6.12.94+deb13-cloud-amd64"},
          {"reference": "linux-headers-6.12.94+deb13-cloud-arm64"},
          {"reference": "linux-headers-6.12.94+deb13-common"},
          {"reference": "linux-headers-6.12.94+deb13-common-rt"},
          {"reference": "linux-headers-6.12.94+deb13-loong64"},
          {"reference": "linux-headers-6.12.94+deb13-loongson-3"},
          {"reference": "linux-headers-6.12.94+deb13-m68k"},
          {"reference": "linux-headers-6.12.94+deb13-mips32r2eb"},
          {"reference": "linux-headers-6.12.94+deb13-mips32r2el"},
          {"reference": "linux-headers-6.12.94+deb13-mips64r2eb"},
          {"reference": "linux-headers-6.12.94+deb13-mips64r2el"}
        ]
      }
    ]
  }
};

var distro_constraints_values = linux_unpatched::get_distro_constraints(distro_constraints_arr:distro_constraints_array);
if (empty_or_null(distro_constraints_values)) audit(AUDIT_HOST_NOT, 'affected');

var third_party_support = get_kb_item('Host/OS/extended-third-party');
if (!empty_or_null(third_party_support)) {
    var third_party_vendors = distro_constraints_values['third_party'];
    if (!empty_or_null(third_party_vendors)) {
        var vendor;
        foreach vendor (third_party_vendors) {
            if (vendor == third_party_support) exit(0, 'A third party management patch is available for this vulnerability from ' + vendor + '.\n');
        }
    }
}

var report = linux_unpatched::check_unpatched_constraints(distro_constraints_values:distro_constraints_values);

if (!empty_or_null(report))
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}