CentOS Linux 8 [TuxCare] Security Update: rsync / rsync-daemon Multiple Vulnerabilities (CENTOS-STREAM8:CLSA-2026:1788773469)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(351507);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/30");

  script_cve_id(
    "CVE-2026-53786",
    "CVE-2026-53789",
    "CVE-2026-70459",
    "CVE-2026-70463"
  );
  script_xref(name:"CLSA", value:"2026:1788773469");

  script_name(english:"CentOS Linux 8 [TuxCare] Security Update: rsync / rsync-daemon Multiple Vulnerabilities (CENTOS-STREAM8:CLSA-2026:1788773469)");

  script_set_attribute(attribute:"synopsis", value:
"The CentOS Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The CentOS Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the
TuxCare CENTOS-STREAM8:CLSA-2026:1788773469 advisory.

  - rsync before 3.5.0 contains a filter rule bypass vulnerability that allows authenticated clients to
    override module-level filter restrictions by supplying malicious --filter merge file directives. Attackers
    can inject client-side merge file directives during filter evaluation to introduce rules that supersede
    daemon module-level restrictions, gaining access to files the module filter was intended to exclude.
    (CVE-2026-53786)

  - rsync before 3.5.0 contains an improper path handling vulnerability that allows a malicious sender to
    expand the scope of --delete operations beyond the intended destination subtree by sending a crafted file
    list that causes rsync to reclassify implied parent directory entries or treat synthetic paths as the
    transfer root. Attackers can exploit multiple variants including implied parent reclassification,
    synthetic root path construction, legacy protocol behavior below version 30, and non-directory root
    handling to cause the receiver to delete files outside the authorized destination directory.
    (CVE-2026-53789)

  - rsync 3.0.0 before 3.5.0 contains a null pointer dereference vulnerability in the daemon child process
    that allows remote attackers to crash the daemon by sending a file list whose first entry is a dot entry
    not typed as a directory. The daemon dereferences the first file list entry as a directory structure
    pointer without verifying the entry type, resulting in an invalid or uninitialized pointer dereference
    that terminates the client connection. (CVE-2026-70459)

  - rsync 3.1.0 before 3.5.0 contains an authorization bypass in auth users directive parsing. The auth users
    parser uses comma-only tokenization when splitting the user list, which fails to correctly handle entries
    of the form @Group Name where the group name contains a space. The space within the group name causes the
    parser to split the entry at the space boundary, discarding the deny rule associated with the group. An
    authenticated user whose username or group membership would be denied by an @Group Name auth users entry
    can connect to a restricted module because the deny rule is silently discarded during parsing.
    (CVE-2026-70463)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  # https://security.tuxcare.com/csaf/v2/els_os/centos-stream8els/advisories/2026/clsa-2026_1788773469.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?b5c1efe6");
  script_set_attribute(attribute:"see_also", value:"https://cve.tuxcare.com/els/releases/CLSA-2026:1788773469");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages based on the guidance in TuxCare advisory CENTOS-STREAM8:CLSA-2026:1788773469.");
  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:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/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-2026-53789");
  script_set_attribute(attribute:"cvss4_score_source", value:"CVE-2026-70463");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/08/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/07");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/30");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"CentOS 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");
  script_require_keys("Host/OS/extended-third-party", "Host/local_checks_enabled", "Host/CentOS/release", "Host/CentOS/rpm-list");

  exit(0);
}
include('rpm2.inc');

var third_party_support = get_kb_item('Host/OS/extended-third-party');
if (empty_or_null(third_party_support) || third_party_support != 'TuxCare') exit(0, 'TuxCare support not enabled.');

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) || 'CentOS Linux' >!< os_product) audit(AUDIT_OS_NOT, 'CentOS Linux');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'CentOS Linux');
if (! preg(pattern:"^8([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'CentOS Linux 8', 'CentOS Linux ' + os_version);

if (!get_kb_item('Host/CentOS/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) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'CentOS Linux', cpu);


var constraints = [
  {
    'release': '8',
    'pkgs': [
      {'reference':'rsync-3.1.3-19.el8.1.tuxcare.els9', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'rsync-daemon-3.1.3-19.el8.1.tuxcare.els9', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

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 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;
  }
  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 &&
        ## (no known rpm to check OR known rpm_exists)
        (!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)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'rsync / rsync-daemon');
}