Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS : Exim vulnerabilities (USN-8834-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8834-1. 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(350975);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/29");

  script_cve_id(
    "CVE-2026-94054",
    "CVE-2026-94055",
    "CVE-2026-94056",
    "CVE-2026-94057"
  );
  script_xref(name:"USN", value:"8834-1");

  script_name(english:"Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS : Exim vulnerabilities (USN-8834-1)");

  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 22.04 LTS / 24.04 LTS / 26.04 LTS host has packages installed that are affected by multiple
vulnerabilities as referenced in the USN-8834-1 advisory.

    It was discovered that Exim had an out-of-bounds write when Proxy-Protocol was used with an attacker-
    controlled proxy. A remote attacker could possibly use this issue to execute arbitrary code.
    (CVE-2026-94054)

    It was discovered that Exim had a use-after-free when certain non-default TLS settings were used with
    GnuTLS. A remote attacker could possibly use this issue to cause Exim to crash, resulting in a denial of
    service. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-94055)

    It was discovered that Exim allowed attackers to read uninitialized data from stack memory when Proxy-
    Protocol was used with an attacker-controlled proxy. A remote attacker could possibly use this issue to
    obtain sensitive information. (CVE-2026-94056)

    It was discovered that Exim allowed SMTP smuggling via crafted data sent after a rejection during DATA
    processing. A remote attacker could possibly use this issue to inject arbitrary email messages.
    (CVE-2026-94057)

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-8834-1");
  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:N/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:U/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: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-2026-94056");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/09/19");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/28");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/29");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:22.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:24.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:26.04:-: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:eximon4");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  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");
  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 (! ('22.04' >< os_release || '24.04' >< os_release || '26.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 22.04 / 24.04 / 26.04', '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 pkgs = [
    {'osver': '22.04', 'pkgname': 'exim4', 'pkgver': '4.95-4ubuntu2.12', 'cves': ['CVE-2026-94054', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '22.04', 'pkgname': 'exim4-base', 'pkgver': '4.95-4ubuntu2.12', 'cves': ['CVE-2026-94054', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '22.04', 'pkgname': 'exim4-config', 'pkgver': '4.95-4ubuntu2.12', 'cves': ['CVE-2026-94054', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '22.04', 'pkgname': 'exim4-daemon-heavy', 'pkgver': '4.95-4ubuntu2.12', 'cves': ['CVE-2026-94054', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '22.04', 'pkgname': 'exim4-daemon-light', 'pkgver': '4.95-4ubuntu2.12', 'cves': ['CVE-2026-94054', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '22.04', 'pkgname': 'eximon4', 'pkgver': '4.95-4ubuntu2.12', 'cves': ['CVE-2026-94054', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '24.04', 'pkgname': 'exim4', 'pkgver': '4.97-4ubuntu4.8', 'cves': ['CVE-2026-94054', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '24.04', 'pkgname': 'exim4-base', 'pkgver': '4.97-4ubuntu4.8', 'cves': ['CVE-2026-94054', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '24.04', 'pkgname': 'exim4-config', 'pkgver': '4.97-4ubuntu4.8', 'cves': ['CVE-2026-94054', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '24.04', 'pkgname': 'exim4-daemon-heavy', 'pkgver': '4.97-4ubuntu4.8', 'cves': ['CVE-2026-94054', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '24.04', 'pkgname': 'exim4-daemon-light', 'pkgver': '4.97-4ubuntu4.8', 'cves': ['CVE-2026-94054', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '24.04', 'pkgname': 'eximon4', 'pkgver': '4.97-4ubuntu4.8', 'cves': ['CVE-2026-94054', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '26.04', 'pkgname': 'exim4', 'pkgver': '4.99.1-1ubuntu1.5', 'cves': ['CVE-2026-94054', 'CVE-2026-94055', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '26.04', 'pkgname': 'exim4-base', 'pkgver': '4.99.1-1ubuntu1.5', 'cves': ['CVE-2026-94054', 'CVE-2026-94055', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '26.04', 'pkgname': 'exim4-config', 'pkgver': '4.99.1-1ubuntu1.5', 'cves': ['CVE-2026-94054', 'CVE-2026-94055', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '26.04', 'pkgname': 'exim4-daemon-heavy', 'pkgver': '4.99.1-1ubuntu1.5', 'cves': ['CVE-2026-94054', 'CVE-2026-94055', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '26.04', 'pkgname': 'exim4-daemon-light', 'pkgver': '4.99.1-1ubuntu1.5', 'cves': ['CVE-2026-94054', 'CVE-2026-94055', 'CVE-2026-94056', 'CVE-2026-94057']},
    {'osver': '26.04', 'pkgname': 'eximon4', 'pkgver': '4.99.1-1ubuntu1.5', 'cves': ['CVE-2026-94054', 'CVE-2026-94055', 'CVE-2026-94056', 'CVE-2026-94057']}
];

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'];
  if (osver && pkgname && pkgver) {
    if (deb_check(release:osver, prefix:pkgname, reference:pkgver, cves:cves)) flag++;
  }
}

if (flag)
{
  var extra = '';
  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');
}