Linux Distros Unpatched Vulnerability : CVE-2026-28753

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

include('compat.inc');

if (description)
{
  script_id(303521);
  script_version("1.11");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/05/18");

  script_cve_id("CVE-2026-28753");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-28753");

  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.

  - NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the
    improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to
    inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note:
    Software versions which have reached End of Technical Support (EoTS) are not evaluated. (CVE-2026-28753)

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-2026-28753");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-28753");
  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:N");
  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:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-28753");

  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:"2026/03/24");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/03/25");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:centos:centos:8");
  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:canonical:ubuntu_linux:nginx");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nginx");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nginx-all-modules");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nginx-core");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nginx-filesystem");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nginx-mod-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nginx-mod-http-image-filter");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nginx-mod-http-perl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nginx-mod-http-xslt-filter");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nginx-mod-mail");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nginx-mod-stream");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-all-modules");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-core");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-filesystem");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-mod-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-mod-http-image-filter");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-mod-http-perl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-mod-http-xslt-filter");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-mod-mail");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-mod-stream");
  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/Red Hat Enterprise Linux-10", "Host/OS/Red Hat Enterprise Linux-8", "Host/OS/Red Hat Enterprise Linux-9", "Host/OS/Ubuntu Linux-14.04", "Host/OS/Ubuntu Linux-16.04", "Host/OS/Ubuntu Linux-18.04", "Host/OS/Ubuntu Linux-20.04");

  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": "nginx"},
          {"reference": "nginx-common"},
          {"reference": "nginx-core"},
          {"reference": "nginx-core-dbg"},
          {"reference": "nginx-doc"},
          {"reference": "nginx-extras"},
          {"reference": "nginx-extras-dbg"},
          {"reference": "nginx-full"},
          {"reference": "nginx-full-dbg"},
          {"reference": "nginx-light"},
          {"reference": "nginx-light-dbg"},
          {"reference": "nginx-naxsi"},
          {"reference": "nginx-naxsi-dbg"},
          {"reference": "nginx-naxsi-ui"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "nginx"},
          {"reference": "nginx-common"},
          {"reference": "nginx-core"},
          {"reference": "nginx-core-dbg"},
          {"reference": "nginx-doc"},
          {"reference": "nginx-extras"},
          {"reference": "nginx-extras-dbg"},
          {"reference": "nginx-full"},
          {"reference": "nginx-full-dbg"},
          {"reference": "nginx-light"},
          {"reference": "nginx-light-dbg"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "libnginx-mod-http-auth-pam"},
          {"reference": "libnginx-mod-http-cache-purge"},
          {"reference": "libnginx-mod-http-dav-ext"},
          {"reference": "libnginx-mod-http-echo"},
          {"reference": "libnginx-mod-http-fancyindex"},
          {"reference": "libnginx-mod-http-geoip"},
          {"reference": "libnginx-mod-http-headers-more-filter"},
          {"reference": "libnginx-mod-http-image-filter"},
          {"reference": "libnginx-mod-http-lua"},
          {"reference": "libnginx-mod-http-ndk"},
          {"reference": "libnginx-mod-http-perl"},
          {"reference": "libnginx-mod-http-subs-filter"},
          {"reference": "libnginx-mod-http-uploadprogress"},
          {"reference": "libnginx-mod-http-upstream-fair"},
          {"reference": "libnginx-mod-http-xslt-filter"},
          {"reference": "libnginx-mod-mail"},
          {"reference": "libnginx-mod-nchan"},
          {"reference": "libnginx-mod-rtmp"},
          {"reference": "libnginx-mod-stream"},
          {"reference": "nginx"},
          {"reference": "nginx-common"},
          {"reference": "nginx-core"},
          {"reference": "nginx-doc"},
          {"reference": "nginx-extras"},
          {"reference": "nginx-full"},
          {"reference": "nginx-light"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "libnginx-mod-http-auth-pam"},
          {"reference": "libnginx-mod-http-cache-purge"},
          {"reference": "libnginx-mod-http-dav-ext"},
          {"reference": "libnginx-mod-http-echo"},
          {"reference": "libnginx-mod-http-fancyindex"},
          {"reference": "libnginx-mod-http-geoip"},
          {"reference": "libnginx-mod-http-geoip2"},
          {"reference": "libnginx-mod-http-headers-more-filter"},
          {"reference": "libnginx-mod-http-image-filter"},
          {"reference": "libnginx-mod-http-lua"},
          {"reference": "libnginx-mod-http-ndk"},
          {"reference": "libnginx-mod-http-perl"},
          {"reference": "libnginx-mod-http-subs-filter"},
          {"reference": "libnginx-mod-http-uploadprogress"},
          {"reference": "libnginx-mod-http-upstream-fair"},
          {"reference": "libnginx-mod-http-xslt-filter"},
          {"reference": "libnginx-mod-mail"},
          {"reference": "libnginx-mod-nchan"},
          {"reference": "libnginx-mod-rtmp"},
          {"reference": "libnginx-mod-stream"},
          {"reference": "nginx"},
          {"reference": "nginx-common"},
          {"reference": "nginx-core"},
          {"reference": "nginx-doc"},
          {"reference": "nginx-extras"},
          {"reference": "nginx-full"},
          {"reference": "nginx-light"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-10": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "10",
        "pkgs": [
          {"reference": "nginx"},
          {"reference": "nginx-all-modules"},
          {"reference": "nginx-core"},
          {"reference": "nginx-filesystem"},
          {"reference": "nginx-mod-devel"},
          {"reference": "nginx-mod-http-image-filter"},
          {"reference": "nginx-mod-http-perl"},
          {"reference": "nginx-mod-http-xslt-filter"},
          {"reference": "nginx-mod-mail"},
          {"reference": "nginx-mod-stream"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-9": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "9",
        "pkgs": [
          {"reference": "nginx"},
          {"reference": "nginx-all-modules"},
          {"reference": "nginx-core"},
          {"reference": "nginx-filesystem"},
          {"reference": "nginx-mod-devel"},
          {"reference": "nginx-mod-http-image-filter"},
          {"reference": "nginx-mod-http-perl"},
          {"reference": "nginx-mod-http-xslt-filter"},
          {"reference": "nginx-mod-mail"},
          {"reference": "nginx-mod-stream"}
        ]
      }
    ]
  },
  "CentOS Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "nginx"},
          {"reference": "nginx-all-modules"},
          {"reference": "nginx-filesystem"},
          {"reference": "nginx-mod-devel"},
          {"reference": "nginx-mod-http-image-filter"},
          {"reference": "nginx-mod-http-perl"},
          {"reference": "nginx-mod-http-xslt-filter"},
          {"reference": "nginx-mod-mail"},
          {"reference": "nginx-mod-stream"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "nginx"},
          {"reference": "nginx-all-modules"},
          {"reference": "nginx-filesystem"},
          {"reference": "nginx-mod-devel"},
          {"reference": "nginx-mod-http-image-filter"},
          {"reference": "nginx-mod-http-perl"},
          {"reference": "nginx-mod-http-xslt-filter"},
          {"reference": "nginx-mod-mail"},
          {"reference": "nginx-mod-stream"}
        ]
      }
    ]
  }
};

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_WARNING,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}