AlmaLinux 9.6 [TuxCare] Security Update: 389-ds-base / 389-ds-base-devel / 389-ds-base-libs / etc Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1789580964)

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

include('compat.inc');

if (description)
{
  script_id(359629);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/01");

  script_cve_id(
    "CVE-2026-18355",
    "CVE-2026-18453",
    "CVE-2026-18922",
    "CVE-2026-76560"
  );
  script_xref(name:"CLSA", value:"2026:1789580964");

  script_name(english:"AlmaLinux 9.6 [TuxCare] Security Update: 389-ds-base / 389-ds-base-devel / 389-ds-base-libs / etc Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1789580964)");

  script_set_attribute(attribute:"synopsis", value:
"The AlmaLinux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The AlmaLinux 9.6 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare
ALMALINUX9.6:CLSA-2026:1789580964 advisory.

  - A heap buffer overflow flaw was found in the SASL I/O layer of 389 Directory Server (389-ds-base). In
    sasl_io_start_packet(), the wrapped-record length read from the wire is validated only against an upper
    bound. A small wire length (0, 1, or 2) produces an encrypted_buffer_count below the already-consumed
    encrypted_buffer_offset, causing an unsigned subtraction underflow in sasl_io_read_packet(). PR_Recv is
    then requested to read approximately 4 GiB into a 1024-byte heap buffer, resulting in a heap buffer
    overflow with attacker-controlled content. After a successful SASL bind with integrity protection (SSF >
    0), a remote authenticated attacker can cause a denial of service or potentially achieve remote code
    execution. This flaw is distinct from CVE-2026-11774, whose fix only guards against upper-bound overflow.
    (CVE-2026-18355)

  - A flaw was found in 389 Directory Server. A missing NULL pointer check in the paged results handling of
    op_shared_search allows an unauthenticated remote attacker to crash the LDAP server by sending a crafted
    sequence of search requests using the USE_ONE_BACKEND control, resulting in denial of service.
    (CVE-2026-18453)

  - A flaw was found in 389 Directory Server. During SASL PLAIN authentication, a stale identity carried in a
    Cyrus SASL auxiliary property from a prior failed bind attempt can be installed on a connection following
    a subsequent, unrelated successful bind, regardless of which SASL mechanism completes that second bind. An
    attacker can send a SASL PLAIN bind as cn=Directory Manager with an incorrect password, then complete a
    SASL ANONYMOUS bind on the same connection, causing the server to grant Directory Manager authority
    without any valid credentials. A variant using a valid low-privileged account's own successful bind
    instead of an anonymous one is also possible. (CVE-2026-18922)

  - A flaw was found in 389 Directory Server. The SELFDN ACI bind-rule evaluator incorrectly matches an
    anonymous LDAP client's empty bind DN against an empty stored attribute value, allowing an unauthenticated
    client to satisfy access control checks intended to require a matching authenticated identity. This can
    allow an anonymous LDAP client to perform an operation, such as adding or modifying a directory entry,
    that a SELFDN-based ACI intended to restrict to a specific authenticated user. (CVE-2026-76560)

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/tuxcare9.6esu/advisories/2026/clsa-2026_1789580964.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?95eae50f");
  script_set_attribute(attribute:"see_also", value:"https://cve.tuxcare.com/els/releases/CLSA-2026:1789580964");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages based on the guidance in TuxCare advisory ALMALINUX9.6:CLSA-2026:1789580964.");
  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:U/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:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-18922");

  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:"Critical");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/09/07");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/16");
  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:"Alma Linux 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/AlmaLinux/release", "Host/AlmaLinux/rpm-list", "Host/cpu");

  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) || 'AlmaLinux' >!< os_product) audit(AUDIT_OS_NOT, 'AlmaLinux');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'AlmaLinux');
if (! preg(pattern:"^9.6([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'AlmaLinux 9.6', 'AlmaLinux ' + os_version);

if (!get_kb_item('Host/AlmaLinux/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, 'AlmaLinux', cpu);


var constraints = [
  {
    'release': '9',
    'sp': '6',
    'pkgs': [
      {'reference':'389-ds-base-2.6.1-12.el9_6.tuxcare.els5', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'389-ds-base-devel-2.6.1-12.el9_6.tuxcare.els5', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'389-ds-base-libs-2.6.1-12.el9_6.tuxcare.els5', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'389-ds-base-snmp-2.6.1-12.el9_6.tuxcare.els5', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'python3-lib389-2.6.1-12.el9_6.tuxcare.els5', 'sp':'6', 'el_string':'el9_6', '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, '389-ds-base / 389-ds-base-devel / 389-ds-base-libs / etc');
}