Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : libpng vulnerabilities (USN-8035-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8035-1. 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(298896);
  script_version("1.4");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/04/30");

  script_cve_id(
    "CVE-2025-66293",
    "CVE-2026-22695",
    "CVE-2026-22801",
    "CVE-2026-25646"
  );
  script_xref(name:"USN", value:"8035-1");
  script_xref(name:"IAVA", value:"2026-A-0135-S");

  script_name(english:"Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : libpng vulnerabilities (USN-8035-1)");

  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 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by multiple
vulnerabilities as referenced in the USN-8035-1 advisory.

    It was discovered that the libpng simplified API incorrectly processed palette PNG images with partial
    transparency and gamma correction. If a user or automated system were tricked into opening a specially
    crafted PNG file, an attacker could use this issue to cause libpng to crash, resulting in a denial of
    service. (CVE-2025-66293)

    Petr Simecek, Stanislav Fort and Pavel Kohout discovered that the libpng simplified API incorrectly
    processed interlaced 16-bit PNGs with 8-bit output format and non-minimal row strides. If a user or
    automated system were tricked into opening a specially crafted PNG file, an attacker could use this issue
    to cause libpng to crash, resulting in a denial of service. (CVE-2026-22695)

    Cosmin Truta discovered that the libpng simplified API incorrectly handled invalid row strides. If a user
    or automated system were tricked into opening a specially crafted PNG file, an attacker could use this
    issue to cause libpng to crash, resulting in a denial of service. This issue only affected Ubuntu 18.04
    LTS and Ubuntu 20.04 LTS. (CVE-2026-22801)

    It was discovered that the libpng simplified API incorrectly handled quantizing RGB images. If a user or
    automated system were tricked into opening a specially crafted PNG file, an attacker could use this issue
    to cause libpng to crash, resulting in a denial of service. (CVE-2026-25646)

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-8035-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/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:H/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:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:P");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-25646");

  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:"2025/12/03");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/02/12");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/02/13");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:libpng-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpng-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpng16-16");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpng16-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpng16-devtools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpng16-tools");
  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 (! ('16.04' >< os_release || '18.04' >< os_release || '20.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 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': '16.04', 'pkgname': 'libpng16-16', 'pkgver': '1.6.20-2ubuntu0.1~esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-66293', 'CVE-2026-22695', 'CVE-2026-25646']},
    {'osver': '16.04', 'pkgname': 'libpng16-dev', 'pkgver': '1.6.20-2ubuntu0.1~esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-66293', 'CVE-2026-22695', 'CVE-2026-25646']},
    {'osver': '16.04', 'pkgname': 'libpng16-devtools', 'pkgver': '1.6.20-2ubuntu0.1~esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-66293', 'CVE-2026-22695', 'CVE-2026-25646']},
    {'osver': '16.04', 'pkgname': 'libpng16-tools', 'pkgver': '1.6.20-2ubuntu0.1~esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-66293', 'CVE-2026-22695', 'CVE-2026-25646']},
    {'osver': '18.04', 'pkgname': 'libpng-dev', 'pkgver': '1.6.34-1ubuntu0.18.04.2+esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-66293', 'CVE-2026-22695', 'CVE-2026-22801', 'CVE-2026-25646']},
    {'osver': '18.04', 'pkgname': 'libpng-tools', 'pkgver': '1.6.34-1ubuntu0.18.04.2+esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-66293', 'CVE-2026-22695', 'CVE-2026-22801', 'CVE-2026-25646']},
    {'osver': '18.04', 'pkgname': 'libpng16-16', 'pkgver': '1.6.34-1ubuntu0.18.04.2+esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-66293', 'CVE-2026-22695', 'CVE-2026-22801', 'CVE-2026-25646']},
    {'osver': '20.04', 'pkgname': 'libpng-dev', 'pkgver': '1.6.37-2ubuntu0.1~esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-66293', 'CVE-2026-22695', 'CVE-2026-22801', 'CVE-2026-25646']},
    {'osver': '20.04', 'pkgname': 'libpng-tools', 'pkgver': '1.6.37-2ubuntu0.1~esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-66293', 'CVE-2026-22695', 'CVE-2026-22801', 'CVE-2026-25646']},
    {'osver': '20.04', 'pkgname': 'libpng16-16', 'pkgver': '1.6.37-2ubuntu0.1~esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-66293', 'CVE-2026-22695', 'CVE-2026-22801', 'CVE-2026-25646']}
];

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, 'libpng-dev / libpng-tools / libpng16-16 / libpng16-dev / etc');
}