TencentOS Server 4: capstone (TSSA-2026:1020)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Tencent Linux Security Advisory TSSA-2026:1020.
##

include('compat.inc');

if (description)
{
  script_id(348669);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/21");

  script_cve_id("CVE-2026-55893", "CVE-2026-55894");

  script_name(english:"TencentOS Server 4: capstone (TSSA-2026:1020)");

  script_set_attribute(attribute:"synopsis", value:
"The remote TencentOS Server 4 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 4 host is prior to tested version. It is,
therefore, affected by multiple vulnerabilities as referenced in the TSSA-2026:1020 advisory.

    Package updates are available for TencentOS Server 4 that fix the following vulnerabilities:

    CVE-2026-55894:
    Capstone is a disassembly framework. In 6.0.0-Alpha9 and earlier, Capstone's arch/SH/SHDisassembler.c
    sh_disassemble() function computes an idx value from a raw 16-bit instruction without ensuring it is
    within the active mode-specific decode[] function-pointer table. An application using CS_ARCH_SH with
    CS_MODE_SH2A or CS_MODE_SH4A and CS_MODE_SHFPU can pass crafted bytecode through cs_disasm_iter() or
    cs_disasm(), causing the decode[idx] test to read outside the table and terminate the process with a
    segmentation fault.

    CVE-2026-55893:
    Capstone is a disassembly framework. In 6.0.0-Alpha9 and earlier, Capstone's arch/SH/SHDisassembler.c SH
    floating-point decoders such as opFADD, opFMUL, and opFSUB call set_reg() and set_reg_n() using
    sh_info.op.op_count without checking the fixed-size operands[] array. Repeated crafted instructions
    processed through cs_disasm_iter() or cs_disasm() with CS_ARCH_SH, CS_MODE_SH2A or CS_MODE_SH4A,
    CS_MODE_SHFPU, and CS_OPT_DETAIL can increment the operand count beyond the 176-byte sh_info allocation
    and perform a four-byte heap buffer overflow write. The corruption can crash the process and may enable
    code execution depending on heap layout. This issue is fixed in version 6.0.0-Alpha10.

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-20261020.xml");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:H/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:L/AC:H/PR:N/UI:R/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:H/AT:P/PR:N/UI:P/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-2026-55893");

  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:"2026/08/20");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/17");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/21");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:tencent:tencentos_server:4");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:tencent:tencentos_server:capstone");
  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:"^4([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'TencentOS 4.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': '4',
    'pkgs': [
      {'reference':'capstone-5.0.1-5.tl4', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'capstone-5.0.1-5.tl4', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'capstone-debuginfo-5.0.1-5.tl4', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'capstone-debuginfo-5.0.1-5.tl4', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'capstone-debugsource-5.0.1-5.tl4', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'capstone-debugsource-5.0.1-5.tl4', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'capstone-devel-5.0.1-5.tl4', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'capstone-devel-5.0.1-5.tl4', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'capstone-java-5.0.1-5.tl4', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'python3-capstone-5.0.1-5.tl4', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'python3-capstone-5.0.1-5.tl4', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'python3-capstone-debuginfo-5.0.1-5.tl4', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'python3-capstone-debuginfo-5.0.1-5.tl4', 'cpu':'x86_64', '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, 'capstone / capstone-debuginfo / capstone-debugsource / etc');
}