Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS : Nano vulnerabilities (USN-8386-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8386-1. 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(318839);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/06/05");

  script_cve_id("CVE-2026-6842", "CVE-2026-6843");
  script_xref(name:"IAVA", value:"2026-A-0513");
  script_xref(name:"USN", value:"8386-1");

  script_name(english:"Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS : Nano vulnerabilities (USN-8386-1)");

  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 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS host has packages installed that are
affected by multiple vulnerabilities as referenced in the USN-8386-1 advisory.

    Micha Majchrowicz and Marcin Wyczechowski discovered that Nano created the ~/.local directory with
    incorrect permissions. In environments with permissive umask settings, a local attacker could possibly use
    this issue to inject a malicious launcher file, resulting in information disclosure or other unintended
    actions. (CVE-2026-6842)

    Micha Majchrowicz and Marcin Wyczechowski discovered that Nano incorrectly handled directory names when
    updating the status line. A local attacker could possibly use this issue to cause Nano to crash, resulting
    in a denial of service. This issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, Ubuntu 25.10, and
    Ubuntu 26.04 LTS. (CVE-2026-6843)

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-8386-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected nano and / or nano-tiny packages.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:H/Au:S/C:N/I:P/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:H/PR:L/UI:N/S:U/C:N/I:L/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-2026-6842");

  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:"2026/04/22");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/06/04");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/06/05");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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: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:25.10");
  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:nano");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:nano-tiny");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_set_attribute(attribute:"stig_severity", value:"II");
  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 (! ('18.04' >< os_release || '20.04' >< os_release || '22.04' >< os_release || '24.04' >< os_release || '25.10' >< os_release || '26.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 18.04 / 20.04 / 22.04 / 24.04 / 25.10 / 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 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': '18.04', 'pkgname': 'nano', 'pkgver': '2.9.3-2ubuntu0.1~esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-6842']},
    {'osver': '18.04', 'pkgname': 'nano-tiny', 'pkgver': '2.9.3-2ubuntu0.1~esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-6842']},
    {'osver': '20.04', 'pkgname': 'nano', 'pkgver': '4.8-1ubuntu1.1+esm1', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-6842']},
    {'osver': '20.04', 'pkgname': 'nano-tiny', 'pkgver': '4.8-1ubuntu1.1+esm1', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-6842']},
    {'osver': '22.04', 'pkgname': 'nano', 'pkgver': '6.2-1ubuntu0.2', 'ubuntu_pro': FALSE, 'cves': ['CVE-2026-6842', 'CVE-2026-6843']},
    {'osver': '22.04', 'pkgname': 'nano-tiny', 'pkgver': '6.2-1ubuntu0.2', 'ubuntu_pro': FALSE, 'cves': ['CVE-2026-6842', 'CVE-2026-6843']},
    {'osver': '24.04', 'pkgname': 'nano', 'pkgver': '7.2-2ubuntu0.2', 'ubuntu_pro': FALSE, 'cves': ['CVE-2026-6842', 'CVE-2026-6843']},
    {'osver': '24.04', 'pkgname': 'nano-tiny', 'pkgver': '7.2-2ubuntu0.2', 'ubuntu_pro': FALSE, 'cves': ['CVE-2026-6842', 'CVE-2026-6843']},
    {'osver': '25.10', 'pkgname': 'nano', 'pkgver': '8.4-1ubuntu0.1', 'ubuntu_pro': FALSE, 'cves': ['CVE-2026-6842', 'CVE-2026-6843']},
    {'osver': '25.10', 'pkgname': 'nano-tiny', 'pkgver': '8.4-1ubuntu0.1', 'ubuntu_pro': FALSE, 'cves': ['CVE-2026-6842', 'CVE-2026-6843']},
    {'osver': '26.04', 'pkgname': 'nano', 'pkgver': '8.7.1-1ubuntu0.1', 'ubuntu_pro': FALSE, 'cves': ['CVE-2026-6842', 'CVE-2026-6843']},
    {'osver': '26.04', 'pkgname': 'nano-tiny', 'pkgver': '8.7.1-1ubuntu0.1', 'ubuntu_pro': FALSE, 'cves': ['CVE-2026-6842', 'CVE-2026-6843']}
];

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_NOTE,
    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, 'nano / nano-tiny');
}