TencentOS Server 3: dovecot (TSSA-2026:0376)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Tencent Linux Security Advisory TSSA-2026:0376.
##

include('compat.inc');

if (description)
{
  script_id(316675);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/05/26");

  script_cve_id("CVE-2025-59032", "CVE-2026-27857", "CVE-2026-27858");

  script_name(english:"TencentOS Server 3: dovecot (TSSA-2026:0376)");

  script_set_attribute(attribute:"synopsis", value:
"The remote TencentOS Server 3 host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The version of Tencent Linux installed on the remote TencentOS Server 3 host is prior to tested version. It is,
therefore, affected by multiple vulnerabilities as referenced in the TSSA-2026:0376 advisory.

    Package updates are available for TencentOS Server 3 that fix the following vulnerabilities:

    CVE-2025-59032:
    ManageSieve AUTHENTICATE command crashes when using literal as SASL initial response. This can be used to
    crash ManageSieve service repeatedly, making it unavailable for other users. Control access to ManageSieve
    port, or disable the service if it's not needed. Alternatively upgrade to a fixed version. No publicly
    available exploits are known.

    CVE-2026-27857:
    Sending NOOP (((...))) command with 4000 parenthesis open+close results in ~1MB extra memory usage.
    Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time
    periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and
    create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and
    killing the process and its other proxied connections. Attacker could connect possibly from even a single
    IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit
    and killing the process and its other proxied connections. Install fixed version, there is no other
    remediation. No publicly available exploits are known.

    CVE-2026-27858:
    Attacker can send a specifically crafted message before authentication that causes managesieve to allocate
    large amount of memory.
     Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access
    to managesieve protocol, or install fixed version. No publicly available exploits are known.

Tenable has extracted the preceding description block directly from the Tencent Linux 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://mirrors.tencent.com/tlinux/errata/tssa-20260376.xml");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/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:N/I:N/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-2026-27857");

  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:"2026/03/27");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/05/05");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/05/26");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:tencent:tencentos_server:3");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:tencent:tencentos_server:dovecot");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Tencent 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/local_checks_enabled", "Host/etc/os-release", "Host/TencentOS/rpm-list", "Host/cpu");

  exit(0);
}


include('rpm2.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) || 'TencentOS' >!< os_product) audit(AUDIT_OS_NOT, 'TencentOS');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'TencentOS');
if (! preg(pattern:"^3([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'TencentOS 3.x', 'TencentOS ' + os_version);

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

var constraints = [
  {
    'release': '3',
    'pkgs': [
      {'reference':'dovecot-2.3.16-7.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-2.3.16-7.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-debuginfo-2.3.16-7.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-debuginfo-2.3.16-7.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-debugsource-2.3.16-7.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-debugsource-2.3.16-7.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-devel-2.3.16-7.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-devel-2.3.16-7.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-mysql-2.3.16-7.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-mysql-2.3.16-7.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-mysql-debuginfo-2.3.16-7.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-mysql-debuginfo-2.3.16-7.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-pgsql-2.3.16-7.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-pgsql-2.3.16-7.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-pgsql-debuginfo-2.3.16-7.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-pgsql-debuginfo-2.3.16-7.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-pigeonhole-2.3.16-7.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-pigeonhole-2.3.16-7.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-pigeonhole-debuginfo-2.3.16-7.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'},
      {'reference':'dovecot-pigeonhole-debuginfo-2.3.16-7.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'1'}
    ]
  }
];

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, 'dovecot / dovecot-debuginfo / dovecot-debugsource / etc');
}