RHEL 8 : brotli (RHSA-2026:90893)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Red Hat Security Advisory RHSA-2026:90893. The text
# itself is copyright (C) Red Hat, Inc.
##

include('compat.inc');

if (description)
{
  script_id(373513);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/30");

  script_cve_id("CVE-2026-111497");
  script_xref(name:"CISA-KNOWN-EXPLOITED", value:"2026/11/10");
  script_xref(name:"RHSA", value:"2026:90893");
  script_xref(name:"IAVA", value:"2026-A-1202");

  script_name(english:"RHEL 8 : brotli (RHSA-2026:90893)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Red Hat host is missing a security update for brotli.");
  script_set_attribute(attribute:"description", value:
"The remote Redhat Enterprise Linux 8 host has packages installed that are affected by a vulnerability as referenced in
the RHSA-2026:90893 advisory.

    Brotli is a generic-purpose lossless compression algorithm that compresses data using a combination of a
    modern variant of the LZ77 algorithm, Huffman coding and 2nd order context modeling, with a compression
    ratio comparable to the best currently available general-purpose compression methods. It is similar in
    speed with deflate but offers more dense compression.

    Security Fix(es):

    * brotli: Out-of-Bounds Write in Google Brotli Decoder (CVE-2026-111497)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and
    other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux 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://access.redhat.com/security/updates/classification/#important");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=2558973");
  # https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_90893.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?08e2761d");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/errata/RHSA-2026:90893");
  script_set_attribute(attribute:"solution", value:
"Update the RHEL brotli package based on the guidance in RHSA-2026:90893.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:H/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:H/RL:O/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:A");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-111497");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_cwe_id(787);
  script_set_attribute(attribute:"vendor_severity", value:"Important");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/10/21");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/10/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/29");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:8");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:rhel_aus:8.6");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:brotli");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:brotli-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:python3-brotli");
  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:"Red Hat 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_info2.nasl", "redhat_repos.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/RedHat/release", "Host/RedHat/rpm-list", "Host/cpu");

  exit(0);
}


include('rpm2.inc');
include('rhel.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_product = get_kb_item('installed_os/local/SSH/0/product');
if (isnull(os_product) || 'Red Hat' >!< os_product) audit(AUDIT_OS_NOT, 'Red Hat');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'Red Hat');
if (!rhel_check_release(operator: 'eq', os_version: os_version, rhel_version: '8.6')) audit(AUDIT_OS_NOT, 'Red Hat 8.6', 'Red Hat ' + os_version);

if (!get_kb_item('Host/RedHat/rpm-list')) 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 && 'ppc' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Red Hat', cpu);

var constraints = [
  {
    'release': '8',
    'sp': '6',
    'repo_relative_urls': [
      'content/aus/rhel8/8.6/x86_64/appstream/debug',
      'content/aus/rhel8/8.6/x86_64/appstream/os',
      'content/aus/rhel8/8.6/x86_64/appstream/source/SRPMS',
      'content/extended-eus/rhel8/8.6/x86_64/appstream/debug',
      'content/extended-eus/rhel8/8.6/x86_64/appstream/os',
      'content/extended-eus/rhel8/8.6/x86_64/appstream/source/SRPMS'
    ],
    'pkgs': [
      {'reference':'brotli-devel-1.0.6-4.el8_6.1', 'sp':'6', 'cpu':'i686', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'brotli-devel-1.0.6-4.el8_6.1', 'sp':'6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'python3-brotli-1.0.6-4.el8_6.1', 'sp':'6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  },
  {
    'release': '8',
    'sp': '6',
    'repo_relative_urls': [
      'content/aus/rhel8/8.6/x86_64/baseos/debug',
      'content/aus/rhel8/8.6/x86_64/baseos/os',
      'content/aus/rhel8/8.6/x86_64/baseos/source/SRPMS',
      'content/extended-eus/rhel8/8.6/x86_64/baseos/debug',
      'content/extended-eus/rhel8/8.6/x86_64/baseos/os',
      'content/extended-eus/rhel8/8.6/x86_64/baseos/source/SRPMS'
    ],
    'pkgs': [
      {'reference':'brotli-1.0.6-4.el8_6.1', 'sp':'6', 'cpu':'i686', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'brotli-1.0.6-4.el8_6.1', 'sp':'6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

var applicable_repo_urls = rhel_determine_applicable_repository_urls(constraints:constraints);
if(applicable_repo_urls == RHEL_REPOS_NO_OVERLAP_MESSAGE) exit(0, RHEL_REPO_NOT_ENABLED);

var os_release = get_one_kb_item('installed_os/local/SSH/0/release');
var os_sp = get_one_kb_item('Host/*/minor_release');

var flag = 0;
var repo_relative_urls;
var reference;
var sp;
var _cpu;
var el_string;
var rpm_spec_vers_cmp;
var epoch;
var allowmaj;
var exists_check;
var cves;
foreach var constraint ( constraints ) {
  # Check that the target release is equal to the affected release
  if (!empty_or_null(constraint['release'])){
    if (constraint['release'] != os_release) continue;
  }
  if (!empty_or_null(constraint['sp'])){
    if (constraint['sp'] != os_sp) continue;
  }

  if (!empty_or_null(constraint['repo_relative_urls'])) repo_relative_urls = constraint['repo_relative_urls'];

  foreach var pkg ( constraint['pkgs'] ) {
    reference = NULL;
    sp = NULL;
    _cpu = NULL;
    el_string = NULL;
    rpm_spec_vers_cmp = NULL;
    epoch = NULL;
    allowmaj = NULL;
    exists_check = NULL;
    cves = NULL;
    if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
    if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
    if (!empty_or_null(pkg['cpu'])) _cpu = pkg['cpu'];
    if (!empty_or_null(pkg['el_string'])) el_string = pkg['el_string'];
    if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
    if (!empty_or_null(pkg['epoch'])) epoch = pkg['epoch'];
    if (!empty_or_null(pkg['allowmaj'])) allowmaj = pkg['allowmaj'];
    if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
    if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
    if (reference &&
        rhel_decide_repo_relative_url_check(required_repo_url_list:repo_relative_urls) &&
        (applicable_repo_urls || (!exists_check || rpm_exists(rpm:exists_check))) &&
        rpm_check(sp:sp, cpu:_cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj, cves:cves)) flag++;
  }
}

if (flag)
{
  var subscription_caveat = '\n' +
    'NOTE: This vulnerability check contains fixes that apply to\n' +
    'packages only available in the Red Hat Enterprise Linux\n' +
    'Advanced Update Support or Extended Update Support repositories.\n' +
    'Access to these repositories requires a paid RHEL subscription.\n';
  var extra = NULL;
  if (isnull(applicable_repo_urls) || !applicable_repo_urls) extra = subscription_caveat + rpm_report_get() + redhat_report_repo_caveat();
  else extra = subscription_caveat + rpm_report_get();
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : extra
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'brotli / brotli-devel / python3-brotli');
}