TencentOS Server 2: freerdp (TSSA-2026:0754)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Tencent Linux Security Advisory TSSA-2026:0754.
##

include('compat.inc');

if (description)
{
  script_id(329210);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/23");

  script_cve_id("CVE-2026-26955", "CVE-2026-26965");
  script_xref(name:"IAVA", value:"2026-A-0257-S");

  script_name(english:"TencentOS Server 2: freerdp (TSSA-2026:0754)");

  script_set_attribute(attribute:"synopsis", value:
"The remote TencentOS Server 2 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 2 host is prior to tested version. It is,
therefore, affected by multiple vulnerabilities as referenced in the TSSA-2026:0754 advisory.

    Package updates are available for TencentOS Server 2 that fix the following vulnerabilities:

    CVE-2026-26955:
    FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, a malicious RDP
    server can trigger a heap buffer overflow in FreeRDP clients using the GDI surface pipeline (e.g.,
    xfreerdp) by sending an RDPGFX ClearCodec surface command with an out-of-bounds destination rectangle. The
    gdi_SurfaceCommand_ClearCodec() handler does not call is_within_surface() to validate the command
    rectangle against the destination surface dimensions, allowing attacker-controlled cmd->left/cmd->top (and
    subcodec rectangle offsets) to reach image copy routines that write into surface->data without bounds
    enforcement. The OOB write corrupts an adjacent gdiGfxSurface struct's codecs* pointer with attacker-
    controlled pixel data, and corruption of codecs* is sufficient to reach an indirect function pointer call
    (NSC_CONTEXT.decode at nsc.c:500) on a subsequent codec command  full instruction pointer (RIP) control
    demonstrated in exploitability harness. Users should upgrade to version 3.23.0 to receive a patch.

    CVE-2026-26965:
    FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, in the RLE
    planar decode path, planar_decompress_plane_rle() writes into pDstData at ((nYDst+y) * nDstStep) +
    (4*nXDst) + nChannel without verifying that (nYDst+nSrcHeight) fits in the destination height or that
    (nXDst+nSrcWidth) fits in the destination stride. When TempFormat != DstFormat, pDstData becomes
    planar->pTempData (sized for the desktop), while nYDst is only validated against the **surface** by
    is_within_surface(). A malicious RDP server can exploit this to perform a heap out-of-bounds write with
    attacker-controlled offset and pixel data on any connecting FreeRDP client. The OOB write reaches up to
    132,096 bytes past the temp buffer end, and  on the brk heap (desktop  128128), an adjacent
    NSC_CONTEXT struct's decode function pointer is overwritten with attacker-controlled pixel data 
    control-flowrelevant corruption (function pointer overwritten) demonstrated under deterministic heap
    layout (nsc->decode = 0xFF414141FF414141). Version 3.23.0 fixes the vulnerability.

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-20260754.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:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-26965");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/02/25");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/04/09");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/23");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:tencent:tencentos_server:2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:tencent:tencentos_server:freerdp");
  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:"^2([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'TencentOS 2.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': '2',
    'pkgs': [
      {'reference':'freerdp-2.1.1-5.tl2.9', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'freerdp-debuginfo-2.1.1-5.tl2.9', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'freerdp-devel-2.1.1-5.tl2.9', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'freerdp-libs-2.1.1-5.tl2.9', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'libwinpr-2.1.1-5.tl2.9', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'libwinpr-devel-2.1.1-5.tl2.9', '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_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, 'freerdp / freerdp-debuginfo / freerdp-devel / etc');
}