Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS : OpenVPN vulnerabilities (USN-8540-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8540-1. 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(326999);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/15");

  script_cve_id(
    "CVE-2026-11771",
    "CVE-2026-12932",
    "CVE-2026-12996",
    "CVE-2026-13117",
    "CVE-2026-13122",
    "CVE-2026-13698"
  );
  script_xref(name:"IAVA", value:"2026-A-0662");
  script_xref(name:"USN", value:"8540-1");

  script_name(english:"Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS : OpenVPN vulnerabilities (USN-8540-1)");

  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 a package installed that is affected by multiple
vulnerabilities as referenced in the USN-8540-1 advisory.

    It was discovered that OpenVPN had a 1-byte buffer overrun when handling NTLMv2 proxy responses. An
    attacker could use this issue to cause a denial of service or possibly execute arbitrary code. This issue
    only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-11771)

    It was discovered that OpenVPN incorrectly handled metadata when extracting tls-crypt-v2 client keys. An
    attacker could possibly use this issue to obtain sensitive information. (CVE-2026-12932)

    It was discovered that OpenVPN had a use-after-free in the ack_write_buf handling. An attacker could use
    this issue to cause OpenVPN to crash, resulting in a denial of service, or possibly execute arbitrary
    code. (CVE-2026-12996)

    It was discovered that OpenVPN had a use-after-free in the tls_wrap_reneg handling. An attacker could use
    this issue to cause OpenVPN to crash, resulting in a denial of service, or possibly execute arbitrary
    code. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-13117)

    It was discovered that OpenVPN incorrectly validated authentication tokens when external authentication
    was enabled. A remote attacker could possibly use this issue to cause OpenVPN to crash, resulting in a
    denial of service. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-13122)

    It was discovered that OpenVPN had a memory leak when handling tls-crypt-v2 client keys. A remote attacker
    with a valid tls-crypt-v2 client key could possibly use this issue to cause OpenVPN to consume excessive
    resources, leading to a denial of service. (CVE-2026-13698)

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-8540-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected openvpn package.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C");
  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:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:U");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-13698");

  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:"2026/07/01");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/07/14");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/15");

  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:openvpn");
  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");
  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': 'openvpn', 'pkgver': '2.5.11-0ubuntu0.22.04.4', 'cves': ['CVE-2026-12932', 'CVE-2026-12996', 'CVE-2026-13698']},
    {'osver': '24.04', 'pkgname': 'openvpn', 'pkgver': '2.6.19-0ubuntu0.24.04.3', 'cves': ['CVE-2026-11771', 'CVE-2026-12932', 'CVE-2026-12996', 'CVE-2026-13117', 'CVE-2026-13122', 'CVE-2026-13698']},
    {'osver': '26.04', 'pkgname': 'openvpn', 'pkgver': '2.7.0-1ubuntu1.2', 'cves': ['CVE-2026-11771', 'CVE-2026-12932', 'CVE-2026-12996', 'CVE-2026-13117', 'CVE-2026-13122', 'CVE-2026-13698']}
];

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, 'openvpn');
}