Debian dsa-6370 : xnest - security update

#%NASL_MIN_LEVEL 80900
#
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Debian Security Advisory dsa-6370. The text
# itself is copyright (C) Software in the Public Interest, Inc.
#

include('compat.inc');

if (description)
{
  script_id(323053);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/06/27");

  script_cve_id(
    "CVE-2026-50256",
    "CVE-2026-50257",
    "CVE-2026-50258",
    "CVE-2026-50259",
    "CVE-2026-50260",
    "CVE-2026-50261",
    "CVE-2026-50262",
    "CVE-2026-50263",
    "CVE-2026-50264"
  );

  script_name(english:"Debian dsa-6370 : xnest - security update");

  script_set_attribute(attribute:"synopsis", value:
"The remote Debian host is missing one or more security-related updates.");
  script_set_attribute(attribute:"description", value:
"The remote Debian 13 host has packages installed that are affected by multiple vulnerabilities as referenced in the
dsa-6370 advisory.

    - -------------------------------------------------------------------------
    Debian Security Advisory DSA-6370-1                   [email protected]
    https://www.debian.org/security/                     Salvatore Bonaccorso
    June 27, 2026                         https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : xorg-server
    CVE ID         : CVE-2026-50256 CVE-2026-50257 CVE-2026-50258 CVE-2026-50259
                     CVE-2026-50260 CVE-2026-50261 CVE-2026-50262 CVE-2026-50263
                     CVE-2026-50264
    Debian Bug     : 1138680

    Several vulnerabilities were discovered in the Xorg X server, which may
    result in privilege escalation if the X server is running privileged.

    For the stable distribution (trixie), these problems have been fixed in
    version 2:21.1.16-1.3+deb13u3.

    We recommend that you upgrade your xorg-server packages.

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

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

    Mailing list: [email protected]

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

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  # https://security-tracker.debian.org/tracker/source-package/xorg-server
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?6c821d87");
  script_set_attribute(attribute:"see_also", value:"https://packages.debian.org/source/trixie/xorg-server");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-50256");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-50257");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-50258");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-50259");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-50260");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-50261");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-50262");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-50263");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-50264");
  script_set_attribute(attribute:"solution", value:
"Upgrade the xnest packages.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-50264");

  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:"2026/06/26");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/06/26");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/06/26");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xnest");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xorg-server-source");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xserver-common");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xserver-xephyr");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xserver-xorg-core");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xserver-xorg-core-udeb");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xserver-xorg-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xserver-xorg-legacy");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xvfb");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:13.0");
  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) 2026 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:"^(13)\.[0-9]+", string:debian_release)) audit(AUDIT_OS_NOT, 'Debian 13.0', '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': '13.0', 'prefix': 'xnest', 'reference': '2:21.1.16-1.3+deb13u3'},
    {'release': '13.0', 'prefix': 'xorg-server-source', 'reference': '2:21.1.16-1.3+deb13u3'},
    {'release': '13.0', 'prefix': 'xserver-common', 'reference': '2:21.1.16-1.3+deb13u3'},
    {'release': '13.0', 'prefix': 'xserver-xephyr', 'reference': '2:21.1.16-1.3+deb13u3'},
    {'release': '13.0', 'prefix': 'xserver-xorg-core', 'reference': '2:21.1.16-1.3+deb13u3'},
    {'release': '13.0', 'prefix': 'xserver-xorg-core-udeb', 'reference': '2:21.1.16-1.3+deb13u3'},
    {'release': '13.0', 'prefix': 'xserver-xorg-dev', 'reference': '2:21.1.16-1.3+deb13u3'},
    {'release': '13.0', 'prefix': 'xserver-xorg-legacy', 'reference': '2:21.1.16-1.3+deb13u3'},
    {'release': '13.0', 'prefix': 'xvfb', 'reference': '2:21.1.16-1.3+deb13u3'}
];

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, 'xnest / xorg-server-source / xserver-common / xserver-xephyr / etc');
}