Debian dla-4625 : dnsmasq - 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-4625. The text
# itself is copyright (C) Software in the Public Interest, Inc.
#

include('compat.inc');

if (description)
{
  script_id(320466);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/06/11");

  script_cve_id(
    "CVE-2026-2291",
    "CVE-2026-4890",
    "CVE-2026-4891",
    "CVE-2026-4892",
    "CVE-2026-4893"
  );
  script_xref(name:"IAVA", value:"2026-A-0450");

  script_name(english:"Debian dla-4625 : dnsmasq - 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 11 host has packages installed that are affected by multiple vulnerabilities as referenced in the
dla-4625 advisory.

    - -------------------------------------------------------------------------
    Debian LTS Advisory DLA-4625-1                [email protected]
    https://www.debian.org/lts/security/                     Arnaud Rebillout
    June 10, 2026                                 https://wiki.debian.org/LTS
    - -------------------------------------------------------------------------

    Package        : dnsmasq
    Version        : 2.85-1+deb11u2
    CVE ID         : CVE-2026-2291 CVE-2026-4890 CVE-2026-4891 CVE-2026-4892
                     CVE-2026-4893

    Several vulnerabilities have been discovered in dnsmasq, a caching DNS
    proxy and DHCP/TFTP server.

    CVE-2026-2291

        dnsmasqs extract_name() function can be abused to cause a heap buffer
        overflow, allowing an attacker to inject false DNS cache entries,
        which could result in DNS lookups to redirect to an
        attacker-controlled IP address, or to cause a DoS.

    CVE-2026-4890

        A Denial of Service (DoS) vulnerability in the DNSSEC validation of
        dnsmasq allows remote attackers to cause a denial of service via a
        crafted DNS packet.

    CVE-2026-4891

        A heap-based out-of-bounds read vulnerability in the DNSSEC validation
        of dnsmasq allows remote attackers to cause a denial of service via a
        crafted DNS packet.

    CVE-2026-4892

        A heap-based out-of-bounds write vulnerability in the DHCPv6
        implementation of dnsmasq allows local attackers to execute arbitrary
        code with root privileges via a crafted DHCPv6 packet.

    CVE-2026-4893

        An information disclosure vulnerability in dnsmasq allows remote
        attackers to bypass source checks via a crafted DNS packet with RFC
        7871 client subnet information.

    For Debian 11 bullseye, these problems have been fixed in version
    2.85-1+deb11u2.

    We recommend that you upgrade your dnsmasq packages.

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

    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 these issues 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/dnsmasq");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-2291");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-4890");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-4891");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-4892");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-4893");
  script_set_attribute(attribute:"see_also", value:"https://packages.debian.org/source/bullseye/dnsmasq");
  script_set_attribute(attribute:"solution", value:
"Upgrade the dnsmasq packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/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:L/AC:L/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:"cvss_score_source", value:"CVE-2026-2291");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2026-4892");

  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:"2026/05/11");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/06/10");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/06/11");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:dnsmasq");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:dnsmasq-base");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:dnsmasq-base-lua");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:dnsmasq-utils");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:11.0");
  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:"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:"^(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': 'dnsmasq', 'reference': '2.85-1+deb11u2'},
    {'release': '11.0', 'prefix': 'dnsmasq-base', 'reference': '2.85-1+deb11u2'},
    {'release': '11.0', 'prefix': 'dnsmasq-base-lua', 'reference': '2.85-1+deb11u2'},
    {'release': '11.0', 'prefix': 'dnsmasq-utils', 'reference': '2.85-1+deb11u2'}
];

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_HOLE,
    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, 'dnsmasq / dnsmasq-base / dnsmasq-base-lua / dnsmasq-utils');
}