TencentOS Server 4: golang (TSSA-2026:0882)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Tencent Linux Security Advisory TSSA-2026:0882.
##

include('compat.inc');

if (description)
{
  script_id(342069);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/01");

  script_cve_id(
    "CVE-2026-33818",
    "CVE-2026-56853",
    "CVE-2026-56858",
    "CVE-2026-56859",
    "CVE-2026-56860",
    "CVE-2026-56862",
    "CVE-2026-56864",
    "CVE-2026-56865"
  );
  script_xref(name:"IAVB", value:"2026-B-0234");

  script_name(english:"TencentOS Server 4: golang (TSSA-2026:0882)");

  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-2026:0882 advisory.

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

    CVE-2026-56865:
    A malicious GOPROXY was previously capable of forging up to two sumdb tiles that allow for a requested
    module to bypass the GOSUMDB check and persist attacker-controlled module content to a local Go module
    cache. This attack allows for a malicious GOPROXY to serve malicious module content that cannot be
    detected by evaluating the transparency log. All tiles are now correctly verified against their parents.

    CVE-2026-56864:
    A malicious GOSUMDB was capable of serving arbitrary module content not contained within the transparency
    log. This attack allows for a coordinating GOPROXY and GOSUMDB to serve a client malicious module content
    that cannot be detected by evaluating the transparency log.

    CVE-2026-56862:
    Handshake messages, such as KeyUpdate, are always considered as state-advancing, regardless of whether a
    handshake has been completed or not. As a result, a malicious client can keep sending KeyUpdate messages
    to force the server to keep performing key derivation operations indefinitely.

    CVE-2026-56860:
    Previously, resolving relative paths containing parent directory ('..') segments performed string
    conversions and buffer rewrites on each step, resulting in quadratic time complexity and high memory
    allocation overhead. Now, path resolution operates on a byte buffer using index-based backtracking for
    '..' segments, eliminating the quadratic time complexity and significantly reducing memory allocations.

    CVE-2026-56859:
    Previously, DecodeElement would reset the depth counter causing it to never fire; this could lead to stack
    exhaustion.

    CVE-2026-56858:
    Previously, pathological inputs could close an unescaped '/' early, allowing for attack-controlled data to
    inject arbitrary content, potentially leading to XSS.

    CVE-2026-56853:
    When a server is configured to support unencrypted HTTP/2, it reads a few bytes from each new connection
    to see if they contain the HTTP/2 client preface. ReadHeaderTimeout is unexpectedly not being applied when
    doing this.

    CVE-2026-33818:
    Enforce a recursion limit in Unmarshal to prevent stack exhaustion when parsing deeply-nested, recursive
    structures.

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-20260882.xml");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:N");
  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: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-2026-56858");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2026-56865");

  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:"2026/08/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/01");

  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:golang");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_set_attribute(attribute:"stig_severity", value:"I");
  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':'golang-1.26.3-2.tl4', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'golang-1.26.3-2.tl4', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'golang-bin-1.26.3-2.tl4', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'golang-bin-1.26.3-2.tl4', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'golang-docs-1.26.3-2.tl4', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'golang-src-1.26.3-2.tl4', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'golang-tests-1.26.3-2.tl4', '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, 'golang / golang-bin / golang-docs / etc');
}