Debian dla-4278 : libmupdf-dev - security update

#%NASL_MIN_LEVEL 80900
#
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Debian Security Advisory dla-4278. The text
# itself is copyright (C) Software in the Public Interest, Inc.
#

include('compat.inc');

if (description)
{
  script_id(253666);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2025/08/22");

  script_cve_id("CVE-2020-21896");

  script_name(english:"Debian dla-4278 : libmupdf-dev - security update");

  script_set_attribute(attribute:"synopsis", value:
"The remote Debian host is missing a security-related update.");
  script_set_attribute(attribute:"description", value:
"The remote Debian 11 host has packages installed that are affected by a vulnerability as referenced in the dla-4278
advisory.

    - -------------------------------------------------------------------------
    Debian LTS Advisory DLA-4278-1                [email protected]
    https://www.debian.org/lts/security/                           Chris Lamb
    August 22, 2025                               https://wiki.debian.org/LTS
    - -------------------------------------------------------------------------

    Package        : mupdf
    Version        : 1.17.0+ds1-2+deb11u1
    CVE ID         : CVE-2020-21896

    It was discovered that there was a potential use after free
    vulnerability in mupdf, a lightweight PDF viewer. This could have
    allowed remote attackers to cause a denial of service attack when
    opening a maliciously-crafted PDF file.

    For Debian 11 bullseye, this problem has been fixed in version
    1.17.0+ds1-2+deb11u1.

    We recommend that you upgrade your mupdf packages.

    For the detailed security status of mupdf please refer to
    its security tracker page at:
    https://security-tracker.debian.org/tracker/mupdf

    Further information about Debian LTS security advisories, how to apply
    these updates to your system and frequently asked questions can be
    found at: https://wiki.debian.org/LTS

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

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/source-package/mupdf");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2020-21896");
  script_set_attribute(attribute:"see_also", value:"https://packages.debian.org/source/bullseye/mupdf");
  script_set_attribute(attribute:"solution", value:
"Upgrade the libmupdf-dev packages.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:N/I:N/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/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-2020-21896");

  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:"2023/08/22");
  script_set_attribute(attribute:"patch_publication_date", value:"2025/08/22");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/08/22");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libmupdf-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:mupdf");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:mupdf-tools");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:11.0");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2025 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/Debian/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);
if (!get_kb_item("Host/Debian/dpkg-l")) audit(AUDIT_PACKAGE_LIST_MISSING);

var debian_release = get_kb_item('Host/Debian/release');
if ( isnull(debian_release) ) audit(AUDIT_OS_NOT, 'Debian');
debian_release = chomp(debian_release);
if (! preg(pattern:"^(11)\.[0-9]+", string:debian_release)) audit(AUDIT_OS_NOT, 'Debian 11.0', 'Debian ' + debian_release);
var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Debian', cpu);

var pkgs = [
    {'release': '11.0', 'prefix': 'libmupdf-dev', 'reference': '1.17.0+ds1-2+deb11u1'},
    {'release': '11.0', 'prefix': 'mupdf', 'reference': '1.17.0+ds1-2+deb11u1'},
    {'release': '11.0', 'prefix': 'mupdf-tools', 'reference': '1.17.0+ds1-2+deb11u1'}
];

var flag = 0;
foreach package_array ( pkgs ) {
  var _release = NULL;
  var prefix = NULL;
  var reference = NULL;
  if (!empty_or_null(package_array['release'])) _release = package_array['release'];
  if (!empty_or_null(package_array['prefix'])) prefix = package_array['prefix'];
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (_release && prefix && reference) {
    if (deb_check(release:_release, prefix:prefix, reference:reference)) flag++;
  }
}

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : deb_report_get()
  );
  exit(0);
}
else
{
  var tested = deb_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'libmupdf-dev / mupdf / mupdf-tools');
}