Amazon Linux 2 : tigervnc (ALAS-2025-2917)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2 Security Advisory ALAS-2025-2917.
##

include('compat.inc');

if (description)
{
  script_id(241768);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2025/07/10");

  script_cve_id(
    "CVE-2025-49175",
    "CVE-2025-49176",
    "CVE-2025-49178",
    "CVE-2025-49179",
    "CVE-2025-49180"
  );

  script_name(english:"Amazon Linux 2 : tigervnc (ALAS-2025-2917)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Amazon Linux 2 host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The version of tigervnc installed on the remote host is prior to 1.8.0-24. It is, therefore, affected by multiple
vulnerabilities as referenced in the ALAS2-2025-2917 advisory.

    A flaw was found in the X Rendering extension's handling of animated cursors. If a client provides no
    cursors, the server assumes at least one is present, leading to an out-of-bounds read and potential crash.
    (CVE-2025-49175)

    A flaw was found in the Big Requests extension. The request length is multiplied by 4 before checking
    against the maximum allowed size, potentially causing an integer overflow and bypassing the size check.
    (CVE-2025-49176)

    A flaw was found in the X server's request handling. Non-zero 'bytes to ignore' in a client's request can
    cause the server to skip processing another client's request, potentially leading to a denial of service.
    (CVE-2025-49178)

    The RecordSanityCheckRegisterClients() function in the X Record extension implementation of the Xserver
    checks for the request length, but does not check for integer overflow.

    A client might send a very large value for either the number of clients or the number of protocol ranges
    that will cause an integer overflow in the request length computation, defeating the check for request
    length. (CVE-2025-49179)

    A flaw was found in the RandR extension, where the RRChangeProviderProperty function does not properly
    validate input. This issue leads to an integer overflow when computing the total size to allocate.
    (CVE-2025-49180)

Tenable has extracted the preceding description block directly from the tested product 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://alas.aws.amazon.com//AL2/ALAS2-2025-2917.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2025-49175.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2025-49176.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2025-49178.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2025-49179.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2025-49180.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/faqs.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update tigervnc' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/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:L/PR:L/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-2025-49180");

  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:"2025/06/17");
  script_set_attribute(attribute:"patch_publication_date", value:"2025/07/10");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/07/10");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:tigervnc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:tigervnc-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:tigervnc-icons");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:tigervnc-license");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:tigervnc-server");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:tigervnc-server-applet");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:tigervnc-server-minimal");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:tigervnc-server-module");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Amazon Linux Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2025 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/AmazonLinux/release", "Host/AmazonLinux/rpm-list");

  exit(0);
}

include("rpm.inc");

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);

var alas_release = get_kb_item("Host/AmazonLinux/release");
if (isnull(alas_release) || !strlen(alas_release)) audit(AUDIT_OS_NOT, "Amazon Linux");
var os_ver = pregmatch(pattern: "^AL(A|\d+|-\d+)", string:alas_release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Amazon Linux");
os_ver = os_ver[1];
if (os_ver != "2")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux 2", "Amazon Linux " + os_ver);
}

if (!get_kb_item("Host/AmazonLinux/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);

var pkgs = [
    {'reference':'tigervnc-1.8.0-24.amzn2.0.6', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-1.8.0-24.amzn2.0.6', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-1.8.0-24.amzn2.0.6', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-debuginfo-1.8.0-24.amzn2.0.6', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-debuginfo-1.8.0-24.amzn2.0.6', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-debuginfo-1.8.0-24.amzn2.0.6', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-icons-1.8.0-24.amzn2.0.6', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-license-1.8.0-24.amzn2.0.6', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-server-1.8.0-24.amzn2.0.6', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-server-1.8.0-24.amzn2.0.6', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-server-1.8.0-24.amzn2.0.6', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-server-applet-1.8.0-24.amzn2.0.6', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-server-minimal-1.8.0-24.amzn2.0.6', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-server-minimal-1.8.0-24.amzn2.0.6', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-server-minimal-1.8.0-24.amzn2.0.6', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-server-module-1.8.0-24.amzn2.0.6', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-server-module-1.8.0-24.amzn2.0.6', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'tigervnc-server-module-1.8.0-24.amzn2.0.6', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var reference = NULL;
  var _release = NULL;
  var sp = NULL;
  var _cpu = NULL;
  var el_string = NULL;
  var rpm_spec_vers_cmp = NULL;
  var epoch = NULL;
  var allowmaj = NULL;
  var exists_check = NULL;
  var cves = NULL;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) _release = package_array['release'];
  if (!empty_or_null(package_array['sp'])) sp = package_array['sp'];
  if (!empty_or_null(package_array['cpu'])) _cpu = package_array['cpu'];
  if (!empty_or_null(package_array['el_string'])) el_string = package_array['el_string'];
  if (!empty_or_null(package_array['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = package_array['rpm_spec_vers_cmp'];
  if (!empty_or_null(package_array['epoch'])) epoch = package_array['epoch'];
  if (!empty_or_null(package_array['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (!empty_or_null(package_array['exists_check'])) exists_check = package_array['exists_check'];
  if (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  if (reference && _release && (!exists_check || rpm_exists(release:_release, rpm:exists_check))) {
    if (rpm_check(release:_release, 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, "tigervnc / tigervnc-debuginfo / tigervnc-icons / etc");
}