Alibaba Cloud Linux 3 : 0327: dovecot (ALINUX3-SA-2026:0327)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The package checks in this plugin were extracted from
# Alibaba Cloud Linux Security Advisory ALINUX3-SA-2026:0327.
##

include('compat.inc');

if (description)
{
  script_id(373496);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/29");

  script_cve_id(
    "CVE-2026-27852",
    "CVE-2026-33263",
    "CVE-2026-33605",
    "CVE-2026-40018",
    "CVE-2026-40019",
    "CVE-2026-42007",
    "CVE-2026-42391",
    "CVE-2026-73208"
  );

  script_name(english:"Alibaba Cloud Linux 3 : 0327: dovecot (ALINUX3-SA-2026:0327)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Alibaba Cloud Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Alibaba Cloud Linux 3 host has packages installed that are affected by multiple vulnerabilities as referenced
in the ALINUX3-SA-2026:0327 advisory.

    Package updates are available for Alibaba Cloud Linux 3 that fix the following vulnerabilities:

    CVE-2026-27852:
    An attacker that can send mail to a user can craft a message whose headers contain a very large number of
    email addresses or MIME parameters, which causes excessive memory usage when the message is later parsed.
    The message is still delivered, but reading it over IMAP can exhaust the memory limit of the process and
    terminate it, causing denial of service for the affected user. Update to non-vulnerable version. No
    publicly available exploits are known.

    CVE-2026-33263:
    When mail_max_userip_connections is set (default 10) and reached, submission-login can crash with epoll()
    panic caused by file descriptor handling issues. If running in high-security mode (default for community
    releases), only the new submission connection gets terminated. If running in high-performance mode
    (default for Pro releases), all connections handled by the submission-login process will be terminated.
    The crashes can cause failure for user to send a message, or it can cause duplicate messages to be sent.
    If TLS is not used (in the backend server processing the submission), duplicate deliveries cannot happen,
    because the crash can only happen at AUTH stage. Limit the number of connections handled by single
    submission-login process. This has a performance impact though. Update to non-vulnerable version. No
    publicly available exploits are known.

    CVE-2026-33605:
    An unauthenticated attacker can crash the ManageSieve login process by sending a small malformed command
    before authenticating. If running in high-security mode (default for community releases), only the
    attacker's own connection is terminated. If running in high-performance mode (default for Pro releases),
    all connections handled by the same managesieve-login process are terminated. Repeating the attack can
    cause denial of service for Sieve script management. Restrict network access to the ManageSieve service to
    trusted clients. Update to non-vulnerable version. No publicly available exploits are known.

    CVE-2026-40018:
    None None None No publicly available exploits are known.

    CVE-2026-40019:
    An unauthenticated attacker can send a truncated quoted argument to the ManageSieve login process, which
    makes it spin in an infinite loop consuming CPU. This can cause degradation or denial of service for Sieve
    script management, and repeated connections can consume all available CPU on the server. Monitor system
    for abnormal CPU usage and kill the offending process. Restrict network access to the ManageSieve service
    to trusted clients. Update to non-vulnerable version. No publicly available exploits are known.

    CVE-2026-42007:
    An attacker that has valid credentials can use a Sieve script with the editheader extension to trigger a
    use-after-free in the mail editing code, and to write memory contents beyond the intended buffer into the
    delivered mail. This causes memory leak and opportunity to do memory corruption during mail delivery,
    which can crash the delivery process and may allow execution of arbitrary code in the context of that
    process. Disable the Sieve editheader extension. Update to non-vulnerable version. No publicly available
    exploits are known.

    CVE-2026-42391:
    An unauthenticated attacker can send an IMAP ID command with a very large number of parameters before
    logging in, which causes memory and CPU usage to grow disproportionately. The login process can be
    terminated by the out-of-memory handling, which also terminates all other connections handled by the same
    process. This can cause degradation or denial of service for IMAP logins. Limit the number of connections
    handled by a single imap-login process. This has a performance impact though. Update to non-vulnerable
    version. No publicly available exploits are known.

    CVE-2026-73208:
    An attacker that holds a token intended for a different purpose can authenticate, because when an OAuth2
    token response does not contain a scope claim, the audience claim is used in its place and checked against
    the configured required scopes. These are different concepts, and the audience claim does not describe
    what a token is allowed to do. A token that grants no relevant permissions can be accepted because its
    intended recipient value happens to match a configured scope name, granting access that should have been
    denied. It also hides an identity provider misconfiguration where scopes are not being issued at all.
    Ensure the identity provider issues a scope claim for all tokens used with Dovecot, and that configured
    scope names do not match audience values. Update to non-vulnerable version. No publicly available exploits
    are known.

Tenable has extracted the preceding description block directly from the Alibaba Cloud 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:"http://mirrors.aliyun.com/alinux/3/cve/alinux3-sa-20260327.xml");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/C:P/I:P/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:L/UI:N/S:C/C:L/I:L/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-2026-42007");

  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:"2026/08/28");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/10/28");
  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:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dovecot");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dovecot-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dovecot-mysql");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dovecot-pgsql");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dovecot-pigeonhole");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alibabacloud:alibaba_cloud_linux_3");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Alibaba Cloud 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/local_checks_enabled", "Host/Alibaba/release", "Host/Alibaba/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) || 'Alibaba Cloud Linux' >!< os_product) audit(AUDIT_OS_NOT, 'Alibaba Cloud Linux');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'Alibaba Cloud Linux');
if (! preg(pattern:"^3([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'Alibaba Cloud Linux 3.x', 'Alibaba Cloud Linux ' + os_version);

if (!get_kb_item('Host/Alibaba/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('aarch64' >!< cpu && 'x86_64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Alibaba Cloud Linux', cpu);

var constraints = [
  {
    'release': '3',
    'pkgs': [
      {'reference':'dovecot-2.3.16-16.0.1.al8', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'dovecot-2.3.16-16.0.1.al8', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'dovecot-devel-2.3.16-16.0.1.al8', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'dovecot-devel-2.3.16-16.0.1.al8', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'dovecot-mysql-2.3.16-16.0.1.al8', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'dovecot-mysql-2.3.16-16.0.1.al8', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'dovecot-pgsql-2.3.16-16.0.1.al8', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'dovecot-pgsql-2.3.16-16.0.1.al8', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'dovecot-pigeonhole-2.3.16-16.0.1.al8', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'dovecot-pigeonhole-2.3.16-16.0.1.al8', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'}
    ]
  }
];

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-devel / dovecot-mysql / dovecot-pgsql / etc');
}