Linux Distros Unpatched Vulnerability : CVE-2021-3595

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

include('compat.inc');

if (description)
{
  script_id(223939);
  script_version("1.5");
  script_set_attribute(attribute:"plugin_modification_date", value:"2025/09/10");

  script_cve_id("CVE-2021-3595");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2021-3595");

  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 invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU. The flaw
    exists in the tftp_input() function and could occur while processing a udp packet that is smaller than the
    size of the 'tftp_t' structure. This issue may lead to out-of-bounds read access or indirect host memory
    disclosure to the guest. The highest threat from this vulnerability is to data confidentiality. This flaw
    affects libslirp versions prior to 4.6.0. (CVE-2021-3595)

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-2021-3595");
  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:P/I:N/A:N");
  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:L/UI:N/S:C/C:L/I:N/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-3595");

  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:"2021/06/15");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/03/05");

  script_set_attribute(attribute:"plugin_type", value:"local");
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  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:8");
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  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");
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  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-device-usb-redirect");
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  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:qemu-kvm-hw-usbredir");
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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-8", "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/RedHat/rpm-list"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "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"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-9": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "9",
        "pkgs": [
          {"reference": "libslirp"},
          {"reference": "libslirp-devel"},
          {"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 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');
}