Linux Distros Unpatched Vulnerability : CVE-2026-93834

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

include('compat.inc');

if (description)
{
  script_id(350663);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/25");

  script_cve_id("CVE-2026-93834");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-93834");

  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.

  - A use-after-free vulnerability was found in QEMU's 9pfs subsystem. A race condition between the main
    thread and a worker thread when processing concurrent Tlcreate and Twalk requests allows a malicious guest
    user to craft a fid path containing stale heap data, bypassing directory traversal restrictions and
    escaping the shared directory boundary. This can lead to arbitrary host file read/write and code execution
    (VM escape) as the QEMU process user. (CVE-2026-93834)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/cve/cve-2026-93834");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-93834");
  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:L/AC:M/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:L/AC:L/PR:L/UI:N/S:C/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-2026-93834");

  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:"2026/09/25");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/25");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:centos:centos:8");
  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:"cpe:/o:redhat:enterprise_linux:10");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:8");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:9");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-guest-agent");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-img");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-audio-pa");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-block-blkio");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-block-curl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-block-gluster");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-block-iscsi");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-block-rbd");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-block-ssh");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-common");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-core");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-device-display-virtio-gpu");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-device-display-virtio-gpu-ccw");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-device-display-virtio-gpu-gl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-device-display-virtio-gpu-pci");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-device-display-virtio-gpu-pci-gl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-device-display-virtio-vga");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-device-display-virtio-vga-gl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-device-usb-host");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-device-usb-redirect");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-docs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-hw-usbredir");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-tests");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-ui-egl-headless");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-ui-opengl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-ui-spice");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-pr-helper");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:qemu");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-guest-agent");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-img");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-audio-pa");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-block-blkio");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-block-curl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-block-gluster");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-block-iscsi");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-block-rbd");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-block-ssh");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-common");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-core");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-device-display-virtio-gpu");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-device-display-virtio-gpu-ccw");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-device-display-virtio-gpu-gl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-device-display-virtio-gpu-pci");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-device-display-virtio-gpu-pci-gl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-device-display-virtio-vga");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-device-display-virtio-vga-gl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-device-usb-host");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-device-usb-redirect");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-docs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-hw-usbredir");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-tests");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-ui-egl-headless");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-ui-opengl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-ui-spice");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-pr-helper");
  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/CentOS Linux-8", "Host/OS/Debian Linux-12", "Host/OS/Debian Linux-13", "Host/OS/Debian Linux-14", "Host/OS/Red Hat Enterprise Linux-10", "Host/OS/Red Hat Enterprise Linux-8", "Host/OS/Red Hat Enterprise Linux-9");

  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/CentOS/rpm-list")) && empty_or_null(get_one_kb_item("Host/Debian/dpkg-l")) && empty_or_null(get_one_kb_item("Host/RedHat/rpm-list"))) 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": "qemu-block-extra"},
          {"reference": "qemu-guest-agent"},
          {"reference": "qemu-system"},
          {"reference": "qemu-system-arm"},
          {"reference": "qemu-system-common"},
          {"reference": "qemu-system-data"},
          {"reference": "qemu-system-gui"},
          {"reference": "qemu-system-mips"},
          {"reference": "qemu-system-misc"},
          {"reference": "qemu-system-ppc"},
          {"reference": "qemu-system-sparc"},
          {"reference": "qemu-system-x86"},
          {"reference": "qemu-system-xen"},
          {"reference": "qemu-user"},
          {"reference": "qemu-user-binfmt"},
          {"reference": "qemu-user-static"},
          {"reference": "qemu-utils"}
        ]
      }
    ]
  },
  "Debian Linux-14": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14",
        "pkgs": [
          {"reference": "qemu-block-extra"},
          {"reference": "qemu-guest-agent"},
          {"reference": "qemu-system"},
          {"reference": "qemu-system-arm"},
          {"reference": "qemu-system-common"},
          {"reference": "qemu-system-data"},
          {"reference": "qemu-system-gui"},
          {"reference": "qemu-system-mips"},
          {"reference": "qemu-system-misc"},
          {"reference": "qemu-system-modules-opengl"},
          {"reference": "qemu-system-modules-spice"},
          {"reference": "qemu-system-ppc"},
          {"reference": "qemu-system-riscv"},
          {"reference": "qemu-system-s390x"},
          {"reference": "qemu-system-sparc"},
          {"reference": "qemu-system-x86"},
          {"reference": "qemu-system-xen"},
          {"reference": "qemu-user"},
          {"reference": "qemu-user-binfmt"},
          {"reference": "qemu-utils"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "qemu-block-extra"},
          {"reference": "qemu-guest-agent"},
          {"reference": "qemu-system"},
          {"reference": "qemu-system-arm"},
          {"reference": "qemu-system-common"},
          {"reference": "qemu-system-data"},
          {"reference": "qemu-system-gui"},
          {"reference": "qemu-system-mips"},
          {"reference": "qemu-system-misc"},
          {"reference": "qemu-system-modules-opengl"},
          {"reference": "qemu-system-modules-spice"},
          {"reference": "qemu-system-ppc"},
          {"reference": "qemu-system-riscv"},
          {"reference": "qemu-system-s390x"},
          {"reference": "qemu-system-sparc"},
          {"reference": "qemu-system-x86"},
          {"reference": "qemu-system-xen"},
          {"reference": "qemu-user"},
          {"reference": "qemu-user-binfmt"},
          {"reference": "qemu-user-static"},
          {"reference": "qemu-utils"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-10": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "10",
        "pkgs": [
          {"reference": "qemu-guest-agent"},
          {"reference": "qemu-img"},
          {"reference": "qemu-kvm"},
          {"reference": "qemu-kvm-audio-pa"},
          {"reference": "qemu-kvm-block-blkio"},
          {"reference": "qemu-kvm-block-curl"},
          {"reference": "qemu-kvm-block-rbd"},
          {"reference": "qemu-kvm-common"},
          {"reference": "qemu-kvm-core"},
          {"reference": "qemu-kvm-device-display-virtio-gpu"},
          {"reference": "qemu-kvm-device-display-virtio-gpu-ccw"},
          {"reference": "qemu-kvm-device-display-virtio-gpu-pci"},
          {"reference": "qemu-kvm-device-display-virtio-vga"},
          {"reference": "qemu-kvm-device-usb-host"},
          {"reference": "qemu-kvm-device-usb-redirect"},
          {"reference": "qemu-kvm-docs"},
          {"reference": "qemu-kvm-tools"},
          {"reference": "qemu-kvm-ui-egl-headless"},
          {"reference": "qemu-kvm-ui-opengl"},
          {"reference": "qemu-pr-helper"}
        ]
      }
    ]
  },
  "CentOS Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "qemu-guest-agent"},
          {"reference": "qemu-img"},
          {"reference": "qemu-kvm"},
          {"reference": "qemu-kvm-block-curl"},
          {"reference": "qemu-kvm-block-gluster"},
          {"reference": "qemu-kvm-block-iscsi"},
          {"reference": "qemu-kvm-block-rbd"},
          {"reference": "qemu-kvm-block-ssh"},
          {"reference": "qemu-kvm-common"},
          {"reference": "qemu-kvm-core"},
          {"reference": "qemu-kvm-docs"},
          {"reference": "qemu-kvm-hw-usbredir"},
          {"reference": "qemu-kvm-tests"},
          {"reference": "qemu-kvm-ui-opengl"},
          {"reference": "qemu-kvm-ui-spice"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "qemu-guest-agent"},
          {"reference": "qemu-img"},
          {"reference": "qemu-kvm"},
          {"reference": "qemu-kvm-block-curl"},
          {"reference": "qemu-kvm-block-gluster"},
          {"reference": "qemu-kvm-block-iscsi"},
          {"reference": "qemu-kvm-block-rbd"},
          {"reference": "qemu-kvm-block-ssh"},
          {"reference": "qemu-kvm-common"},
          {"reference": "qemu-kvm-core"},
          {"reference": "qemu-kvm-docs"},
          {"reference": "qemu-kvm-hw-usbredir"},
          {"reference": "qemu-kvm-tests"},
          {"reference": "qemu-kvm-ui-opengl"},
          {"reference": "qemu-kvm-ui-spice"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-9": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "9",
        "pkgs": [
          {"reference": "qemu-guest-agent"},
          {"reference": "qemu-img"},
          {"reference": "qemu-kvm"},
          {"reference": "qemu-kvm-audio-pa"},
          {"reference": "qemu-kvm-block-blkio"},
          {"reference": "qemu-kvm-block-curl"},
          {"reference": "qemu-kvm-block-rbd"},
          {"reference": "qemu-kvm-common"},
          {"reference": "qemu-kvm-core"},
          {"reference": "qemu-kvm-device-display-virtio-gpu"},
          {"reference": "qemu-kvm-device-display-virtio-gpu-ccw"},
          {"reference": "qemu-kvm-device-display-virtio-gpu-gl"},
          {"reference": "qemu-kvm-device-display-virtio-gpu-pci"},
          {"reference": "qemu-kvm-device-display-virtio-gpu-pci-gl"},
          {"reference": "qemu-kvm-device-display-virtio-vga"},
          {"reference": "qemu-kvm-device-display-virtio-vga-gl"},
          {"reference": "qemu-kvm-device-usb-host"},
          {"reference": "qemu-kvm-device-usb-redirect"},
          {"reference": "qemu-kvm-docs"},
          {"reference": "qemu-kvm-tools"},
          {"reference": "qemu-kvm-ui-egl-headless"},
          {"reference": "qemu-kvm-ui-opengl"},
          {"reference": "qemu-pr-helper"}
        ]
      }
    ]
  }
};

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');
}