Debian dla-4622 : libxml2 - 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-4622. The text
# itself is copyright (C) Software in the Public Interest, Inc.
#

include('compat.inc');

if (description)
{
  script_id(319670);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/06/09");

  script_cve_id(
    "CVE-2025-8732",
    "CVE-2026-0989",
    "CVE-2026-0990",
    "CVE-2026-0992",
    "CVE-2026-1757"
  );
  script_xref(name:"IAVA", value:"2025-A-0840-S");

  script_name(english:"Debian dla-4622 : libxml2 - 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-4622 advisory.

    -------------------------------------------------------------------------
    Debian LTS Advisory DLA-4622-1                [email protected]
    https://www.debian.org/lts/security/                       Guilhem Moulin
    June 08, 2026                                 https://wiki.debian.org/LTS
    -------------------------------------------------------------------------

    Package        : libxml2
    Version        : 2.9.10+dfsg-6.7+deb11u10
    CVE ID         : CVE-2025-8732 CVE-2026-0989 CVE-2026-0990 CVE-2026-0992
                     CVE-2026-1757
    Debian Bug     : 1125691 1125695 1125696

    Multiple security issues were found in libxml2, the GNOME XML library,
    which could lead to Denial of Service.

    CVE-2025-8732

        Catalog parsing functions were missing cycle detection.  When a
        catalog file contains a CATALOG directive pointing to itself,
        `xmlExpandCatalog()` and `xmlParseSGMLCatalog()` recursively call
        each other without bounds until stack overflow.

    CVE-2026-0989

        The RelaxNG parser does not limit the recursion depth when resolving
        `<include>` directives, which may lead to stack overflow on
        malicious RelaxNG schema file.

    CVE-2026-0990

        Nick Wellnhofer discovered that `xmlCatalogXMLResolveURI()` will
        recurse infinitely if a catalog has a URI delegate referencing
        itself, eventually resulting in a call stack overflow.

    CVE-2026-0992

        Nick Wellnhofer discovered that processing a chain of XML catalogs
        linked with `<nextCatalog>` and having the `<nextCatalog>` element
        takes exponential time, leading to denial of service via resource
        exhaustion.

    CVE-2026-1757

        The command parsing logic of the xmllint(1) interactive shell was
        found to leak memory.

    In addition, a few other security issues were found for which no CVE ID
    was assigned yet:

       * Memory leak of prefix in `xmlTextWriterStartElementNS()`.

       * Potential use-after-free issue in `xmlRelaxNGValidateValue()`.

       * Memory leak in `xmlTextWriterStartAttributeNS()`.

       * Additional memory leaks on error paths in schematron.

       * Stack overflow from self-referencing SGML CATALOG entries.

    For Debian 11 bullseye, these problems have been fixed in version
    2.9.10+dfsg-6.7+deb11u10.

    We recommend that you upgrade your libxml2 packages.

    For the detailed security status of libxml2 please refer to
    its security tracker page at:
    https://security-tracker.debian.org/tracker/libxml2

    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
    Attachment:
    signature.asc
    Description: PGP signature

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/libxml2");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2025-8732");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-0989");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-0990");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-0992");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-1757");
  script_set_attribute(attribute:"see_also", value:"https://packages.debian.org/source/bullseye/libxml2");
  script_set_attribute(attribute:"solution", value:
"Upgrade the libxml2 packages.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:P");
  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: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:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/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-2025-8732");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2026-1757");

  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:"2025/08/08");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/06/08");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/06/08");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libxml2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libxml2-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libxml2-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libxml2-utils");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:python3-libxml2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:python3-libxml2-dbg");
  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': 'libxml2', 'reference': '2.9.10+dfsg-6.7+deb11u10'},
    {'release': '11.0', 'prefix': 'libxml2-dev', 'reference': '2.9.10+dfsg-6.7+deb11u10'},
    {'release': '11.0', 'prefix': 'libxml2-doc', 'reference': '2.9.10+dfsg-6.7+deb11u10'},
    {'release': '11.0', 'prefix': 'libxml2-utils', 'reference': '2.9.10+dfsg-6.7+deb11u10'},
    {'release': '11.0', 'prefix': 'python3-libxml2', 'reference': '2.9.10+dfsg-6.7+deb11u10'},
    {'release': '11.0', 'prefix': 'python3-libxml2-dbg', 'reference': '2.9.10+dfsg-6.7+deb11u10'}
];

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_NOTE,
    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, 'libxml2 / libxml2-dev / libxml2-doc / libxml2-utils / python3-libxml2 / etc');
}