Linux Distros Unpatched Vulnerability : CVE-2026-27651

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

include('compat.inc');

if (description)
{
  script_id(303484);
  script_version("1.15");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/05/18");

  script_cve_id("CVE-2026-27651");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-27651");

  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.

  - When the ngx_mail_auth_http_module module is enabled on NGINX Plus or NGINX Open Source, undisclosed
    requests can cause worker processes to terminate. This issue may occur when (1) CRAM-MD5 or APOP
    authentication is enabled, and (2) the authentication server permits retry by returning the Auth-Wait
    response header. Note: Software versions which have reached End of Technical Support (EoTS) are not
    evaluated. (CVE-2026-27651)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-27651");
  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:M/Au:N/C:P/I:N/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:N/I:N/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-2026-27651");

  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:"2026/03/24");

  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:"p-cpe:/a:canonical:ubuntu_linux:nginx");
  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/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/Debian/dpkg-l"))) 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"}
        ]
      }
    ]
  }
};

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');
}