CentOS Linux 8 [TuxCare] Security Update: rsync / rsync-daemon Multiple Vulnerabilities (CENTOS-STREAM8:CLSA-2026:1788959958)

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

include('compat.inc');

if (description)
{
  script_id(359657);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/02");

  script_cve_id("CVE-2026-53784", "CVE-2026-53802", "CVE-2026-53803");
  script_xref(name:"CLSA", value:"2026:1788959958");

  script_name(english:"CentOS Linux 8 [TuxCare] Security Update: rsync / rsync-daemon Multiple Vulnerabilities (CENTOS-STREAM8:CLSA-2026:1788959958)");

  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-2026:1788959958 advisory.

  - rsync before 3.5.0 contains a path traversal vulnerability that allows remote clients to access files
    outside the intended module root when use chroot is disabled and the module root path or a component of it
    is a symlink. The daemon calls chdir() to the module root at session initialization without resolving
    symlinks via realpath() or equivalent, causing subsequent relative-path operations to reference files
    relative to the symlink target rather than the intended module root, enabling unauthorized file access.
    (CVE-2026-53784)

  - rsync before 3.5.0 contains an arbitrary file read vulnerability that allows attackers to read files
    accessible to the rsync daemon process by exploiting symlink following in input configuration file
    handling including --files-from, --password-file, and filter merge files. Attackers can place a symlink at
    a predictable --files-from or --password-file path, or supply a --files-from path that escapes the daemon
    module root, to read arbitrary files accessible to the rsync process. (CVE-2026-53802)

  - rsync before 3.5.0 contains a symlink following vulnerability that allows local attackers to overwrite
    arbitrary files by placing a symlink at a predictable output path such as --log-file, --write-batch, or
    daemon-mode log and statistics paths. Attackers can exploit rsync's failure to reject symlinks during
    ancillary file writes to redirect output to arbitrary filesystem locations, achieving local privilege
    escalation on installations where rsync runs with elevated privileges such as setuid or privileged daemon
    configurations. (CVE-2026-53803)

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_1788959958.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?7e2b58f1");
  script_set_attribute(attribute:"see_also", value:"https://cve.tuxcare.com/els/releases/CLSA-2026:1788959958");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages based on the guidance in TuxCare advisory CENTOS-STREAM8:CLSA-2026:1788959958.");
  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:"cvss4_vector", value:"CVSS:4.0/AV:L/AC:L/AT:N/PR:L/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:U");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-53803");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_set_attribute(attribute:"vendor_severity", value:"Important");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/08/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/09");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/01");

  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.els10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'rsync-daemon-3.1.3-19.el8.1.tuxcare.els10', '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_WARNING,
      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');
}