Linux Distros Unpatched Vulnerability : CVE-2021-20221

##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(223660);
  script_version("1.4");
  script_set_attribute(attribute:"plugin_modification_date", value:"2025/09/10");

  script_cve_id("CVE-2021-20221");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2021-20221");

  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.

  - An out-of-bounds heap buffer access issue was found in the ARM Generic Interrupt Controller emulator of
    QEMU up to and including qemu 4.2.0on aarch64 platform. The issue occurs because while writing an
    interrupt ID to the controller memory area, it is not masked to be 4 bits wide. It may lead to the said
    issue while updating controller state fields and their subsequent processing. A privileged guest user may
    use this flaw to crash the QEMU process on the host resulting in DoS scenario. (CVE-2021-20221)

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-2021-20221");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2021-20221");
  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:L/Au:N/C:N/I:N/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-20221");

  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:"2020/12/03");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/03/04");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:redhat:advanced_virtualization:8::el8");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:14.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:centos:centos:7");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:centos:centos:8");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:7");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:8");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:qemu");
  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-img-ma");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-img-rhev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kiwi");
  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-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-common-ma");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-common-rhev");
  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-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-ma");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-rhev");
  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-ma");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-tools-rhev");
  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:redhat:enterprise_linux:qemu-guest-agent");
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  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-img-ma");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-img-rhev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kiwi");
  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-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-common-ma");
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  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-ma");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:qemu-kvm-rhev");
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  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

  script_copyright(english:"This script is Copyright (C) 2025 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("set_linux_os_id.nasl", "ssh_get_info2.nasl");
  script_require_keys("Host/OS/identifier", "Host/cpu", "Host/local_checks_enabled", "global_settings/vendor_unpatched");
  script_require_ports("Host/OS/CentOS Linux-7", "Host/OS/CentOS Linux-8", "Host/OS/Red Hat Enterprise Linux-7", "Host/OS/Red Hat Enterprise Linux-8", "Host/OS/Ubuntu Linux-14.04", "Host/OS/Ubuntu Linux-16.04");

  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 = {
  "Ubuntu Linux-14.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14.04",
        "pkgs": [
          {"reference": "qemu"},
          {"reference": "qemu-common"},
          {"reference": "qemu-guest-agent"},
          {"reference": "qemu-keymaps"},
          {"reference": "qemu-kvm"},
          {"reference": "qemu-system"},
          {"reference": "qemu-system-aarch64"},
          {"reference": "qemu-system-arm"},
          {"reference": "qemu-system-common"},
          {"reference": "qemu-system-mips"},
          {"reference": "qemu-system-misc"},
          {"reference": "qemu-system-ppc"},
          {"reference": "qemu-system-sparc"},
          {"reference": "qemu-system-x86"},
          {"reference": "qemu-user"},
          {"reference": "qemu-user-static"},
          {"reference": "qemu-utils"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "qemu"},
          {"reference": "qemu-block-extra"},
          {"reference": "qemu-guest-agent"},
          {"reference": "qemu-kvm"},
          {"reference": "qemu-system"},
          {"reference": "qemu-system-aarch64"},
          {"reference": "qemu-system-arm"},
          {"reference": "qemu-system-common"},
          {"reference": "qemu-system-mips"},
          {"reference": "qemu-system-misc"},
          {"reference": "qemu-system-ppc"},
          {"reference": "qemu-system-s390x"},
          {"reference": "qemu-system-sparc"},
          {"reference": "qemu-system-x86"},
          {"reference": "qemu-user"},
          {"reference": "qemu-user-binfmt"},
          {"reference": "qemu-user-static"},
          {"reference": "qemu-utils"}
        ]
      }
    ]
  },
  "CentOS Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "qemu-img-ma"},
          {"reference": "qemu-img-rhev"},
          {"reference": "qemu-kvm-common-ma"},
          {"reference": "qemu-kvm-common-rhev"},
          {"reference": "qemu-kvm-ma"},
          {"reference": "qemu-kvm-rhev"},
          {"reference": "qemu-kvm-tools-ma"},
          {"reference": "qemu-kvm-tools-rhev"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "qemu-img-ma"},
          {"reference": "qemu-img-rhev"},
          {"reference": "qemu-kvm-common-ma"},
          {"reference": "qemu-kvm-common-rhev"},
          {"reference": "qemu-kvm-ma"},
          {"reference": "qemu-kvm-rhev"},
          {"reference": "qemu-kvm-tools-ma"},
          {"reference": "qemu-kvm-tools-rhev"}
        ]
      }
    ]
  },
  "CentOS Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "qemu-guest-agent"},
          {"reference": "qemu-img"},
          {"reference": "qemu-kiwi"},
          {"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-kiwi"},
          {"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"}
        ]
      }
    ]
  }
};

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

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