Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS : Exim vulnerabilities (USN-8382-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8382-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('compat.inc');

if (description)
{
  script_id(318625);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/06/04");

  script_cve_id(
    "CVE-2023-51766",
    "CVE-2026-40685",
    "CVE-2026-40686",
    "CVE-2026-40687",
    "CVE-2026-45185",
    "CVE-2026-48840"
  );
  script_xref(name:"IAVA", value:"2024-A-0002-S");
  script_xref(name:"IAVA", value:"2026-A-0417-S");
  script_xref(name:"IAVA", value:"2026-A-0478");
  script_xref(name:"USN", value:"8382-1");

  script_name(english:"Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS : Exim vulnerabilities (USN-8382-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by
multiple vulnerabilities as referenced in the USN-8382-1 advisory.

    Timo Longin discovered that Exim incorrectly handled certain SMTP messages in PIPELINING/CHUNKING
    configurations. A remote attacker could possibly use this issue to perform SMTP smuggling. This issue only
    affected Ubuntu 14.04 LTS. (CVE-2023-51766)

    It was discovered that Exim incorrectly handled certain malformed JSON data in headers. A remote attacker
    could possibly use this issue to crash Exim, resulting in a denial of service, or execute arbitrary code.
    This issue only affected Ubuntu 20.04 LTS. (CVE-2026-40685)

    It was discovered that Exim incorrectly handled certain malformed UTF-8 headers. A remote attacker could
    possibly use this issue to obtain sensitive information. This issue only affected Ubuntu 20.04 LTS.
    (CVE-2026-40686)

    It was discovered that Exim incorrectly handled certain SPA resources. A remote attacker could possibly
    use this issue to crash Exim, resulting in a denial of service, or obtain sensitive information. This
    issue only affected Ubuntu 20.04 LTS. (CVE-2026-40687)

    It was discovered that Exim incorrectly handled certain CHUNKING transfers in some GnuTLS configurations.
    A remote attacker could possibly use this issue to crash Exim, resulting in a denial of service, or
    execute arbitrary code. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-45185)

    Warisjeet Singh discovered that Exim incorrectly handled certain proxy connections in builds with proxy
    support enabled. A remote attacker could possibly use this issue to obtain sensitive information. This
    issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2026-48840)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/notices/USN-8382-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/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:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-40685");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2023/12/24");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/06/03");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/06/04");

  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:exim4");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:exim4-base");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:exim4-config");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:exim4-daemon-heavy");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:exim4-daemon-light");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:exim4-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:eximon4");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Ubuntu Local Security Checks");

  script_copyright(english:"Ubuntu Security Notice (C) 2026 Canonical, Inc. / NASL script (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl", "ubuntu_pro_sub_detect.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('14.04' >< os_release || '16.04' >< os_release || '18.04' >< os_release || '20.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 14.04 / 16.04 / 18.04 / 20.04', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Ubuntu', cpu);
var ubuntu_pro_detected = get_kb_item('Host/Ubuntu/Pro/Services/esm-apps');
ubuntu_pro_detected = !empty_or_null(ubuntu_pro_detected);

var pro_caveat_needed = FALSE;

var pkgs = [
    {'osver': '14.04', 'pkgname': 'exim4', 'pkgver': '4.82-3ubuntu2.4+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2023-51766']},
    {'osver': '14.04', 'pkgname': 'exim4-base', 'pkgver': '4.82-3ubuntu2.4+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2023-51766']},
    {'osver': '14.04', 'pkgname': 'exim4-config', 'pkgver': '4.82-3ubuntu2.4+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2023-51766']},
    {'osver': '14.04', 'pkgname': 'exim4-daemon-heavy', 'pkgver': '4.82-3ubuntu2.4+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2023-51766']},
    {'osver': '14.04', 'pkgname': 'exim4-daemon-light', 'pkgver': '4.82-3ubuntu2.4+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2023-51766']},
    {'osver': '14.04', 'pkgname': 'exim4-dev', 'pkgver': '4.82-3ubuntu2.4+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2023-51766']},
    {'osver': '14.04', 'pkgname': 'eximon4', 'pkgver': '4.82-3ubuntu2.4+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2023-51766']},
    {'osver': '16.04', 'pkgname': 'exim4', 'pkgver': '4.86.2-2ubuntu2.6+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '16.04', 'pkgname': 'exim4-base', 'pkgver': '4.86.2-2ubuntu2.6+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '16.04', 'pkgname': 'exim4-config', 'pkgver': '4.86.2-2ubuntu2.6+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '16.04', 'pkgname': 'exim4-daemon-heavy', 'pkgver': '4.86.2-2ubuntu2.6+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '16.04', 'pkgname': 'exim4-daemon-light', 'pkgver': '4.86.2-2ubuntu2.6+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '16.04', 'pkgname': 'exim4-dev', 'pkgver': '4.86.2-2ubuntu2.6+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '16.04', 'pkgname': 'eximon4', 'pkgver': '4.86.2-2ubuntu2.6+esm9', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '18.04', 'pkgname': 'exim4', 'pkgver': '4.90.1-1ubuntu1.10+esm6', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '18.04', 'pkgname': 'exim4-base', 'pkgver': '4.90.1-1ubuntu1.10+esm6', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '18.04', 'pkgname': 'exim4-config', 'pkgver': '4.90.1-1ubuntu1.10+esm6', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '18.04', 'pkgname': 'exim4-daemon-heavy', 'pkgver': '4.90.1-1ubuntu1.10+esm6', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '18.04', 'pkgname': 'exim4-daemon-light', 'pkgver': '4.90.1-1ubuntu1.10+esm6', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '18.04', 'pkgname': 'exim4-dev', 'pkgver': '4.90.1-1ubuntu1.10+esm6', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '18.04', 'pkgname': 'eximon4', 'pkgver': '4.90.1-1ubuntu1.10+esm6', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-48840']},
    {'osver': '20.04', 'pkgname': 'exim4', 'pkgver': '4.93-13ubuntu1.12+esm1', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-40685', 'CVE-2026-40686', 'CVE-2026-40687', 'CVE-2026-45185', 'CVE-2026-48840']},
    {'osver': '20.04', 'pkgname': 'exim4-base', 'pkgver': '4.93-13ubuntu1.12+esm1', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-40685', 'CVE-2026-40686', 'CVE-2026-40687', 'CVE-2026-45185', 'CVE-2026-48840']},
    {'osver': '20.04', 'pkgname': 'exim4-config', 'pkgver': '4.93-13ubuntu1.12+esm1', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-40685', 'CVE-2026-40686', 'CVE-2026-40687', 'CVE-2026-45185', 'CVE-2026-48840']},
    {'osver': '20.04', 'pkgname': 'exim4-daemon-heavy', 'pkgver': '4.93-13ubuntu1.12+esm1', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-40685', 'CVE-2026-40686', 'CVE-2026-40687', 'CVE-2026-45185', 'CVE-2026-48840']},
    {'osver': '20.04', 'pkgname': 'exim4-daemon-light', 'pkgver': '4.93-13ubuntu1.12+esm1', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-40685', 'CVE-2026-40686', 'CVE-2026-40687', 'CVE-2026-45185', 'CVE-2026-48840']},
    {'osver': '20.04', 'pkgname': 'exim4-dev', 'pkgver': '4.93-13ubuntu1.12+esm1', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-40685', 'CVE-2026-40686', 'CVE-2026-40687', 'CVE-2026-45185', 'CVE-2026-48840']},
    {'osver': '20.04', 'pkgname': 'eximon4', 'pkgver': '4.93-13ubuntu1.12+esm1', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-40685', 'CVE-2026-40686', 'CVE-2026-40687', 'CVE-2026-45185', 'CVE-2026-48840']}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var osver = NULL;
  var pkgname = NULL;
  var pkgver = NULL;
  if (!empty_or_null(package_array['osver'])) osver = package_array['osver'];
  if (!empty_or_null(package_array['pkgname'])) pkgname = package_array['pkgname'];
  if (!empty_or_null(package_array['pkgver'])) pkgver = package_array['pkgver'];
  if (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  var pro_required = NULL;
  if (!empty_or_null(package_array['ubuntu_pro'])) pro_required = package_array['ubuntu_pro'];
  if (osver && pkgname && pkgver) {
    if (deb_check(release:osver, prefix:pkgname, reference:pkgver, cves:cves)) {
        flag++;
        if (!ubuntu_pro_detected && !pro_caveat_needed) pro_caveat_needed = pro_required;
    }
  }
}

if (flag)
{
  var extra = '';
  if (pro_caveat_needed) {
    extra += 'NOTE: This vulnerability check contains fixes that apply to packages only \n';
    extra += 'available in Ubuntu ESM repositories. Access to these package security updates \n';
    extra += 'require an Ubuntu Pro subscription.\n\n';
  }
  extra += ubuntu_report_get();
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'exim4 / exim4-base / exim4-config / exim4-daemon-heavy / etc');
}