Azure Linux 3.0 Security Update: kernel (CVE-2025-21915)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(296052);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/01/22");

  script_cve_id("CVE-2025-21915");

  script_name(english:"Azure Linux 3.0 Security Update: kernel (CVE-2025-21915)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Azure Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The version of kernel installed on the remote Azure Linux 3.0 host is prior to tested version. It is, therefore,
affected by a vulnerability as referenced in the CVE-2025-21915 advisory.

  - In the Linux kernel, the following vulnerability has been resolved: cdx: Fix possible UAF error in
    driver_override_show() Fixed a possible UAF problem in driver_override_show() in drivers/cdx/cdx.c This
    function driver_override_show() is part of DEVICE_ATTR_RW, which includes both driver_override_show() and
    driver_override_store(). These functions can be executed concurrently in sysfs. The
    driver_override_store() function uses driver_set_override() to update the driver_override value, and
    driver_set_override() internally locks the device (device_lock(dev)). If driver_override_show() reads
    cdx_dev->driver_override without locking, it could potentially access a freed pointer if
    driver_override_store() frees the string concurrently. This could lead to printing a kernel address, which
    is a security risk since DEVICE_ATTR can be read by all users. Additionally, a similar pattern is used in
    drivers/amba/bus.c, as well as many other bus drivers, where device_lock() is taken in the show function,
    and it has been working without issues. This potential bug was detected by our experimental static
    analysis tool, which analyzes locking APIs and paired functions to identify data races and atomicity
    violations. (CVE-2025-21915)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2025-21915");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  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-2025-21915");

  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:"2025/04/01");
  script_set_attribute(attribute:"patch_publication_date", value:"2025/05/13");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/01/22");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:bpftool");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-docs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-drivers-accessibility");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-drivers-gpu");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-drivers-intree-amdgpu");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-drivers-sound");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:python3-perf");
  script_set_attribute(attribute:"cpe", value:"x-cpe:/o:microsoft:azure_linux");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Azure 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/AzureLinux/release", "Host/AzureLinux/rpm-list", "Host/cpu");

  exit(0);
}
include('rpm.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var release = get_kb_item('Host/AzureLinux/release');
if (isnull(release) || 'Azure Linux' >!< release) audit(AUDIT_OS_NOT, 'Azure Linux');
var os_ver = pregmatch(pattern: "Azure Linux ([0-9]+(\.[0-9]+)?)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, 'Azure Linux');
os_ver = os_ver[1];
if (! preg(pattern:"^3([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, 'Azure Linux 3.0', 'Azure Linux ' + os_ver);

if (!get_kb_item('Host/AzureLinux/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$" && 'aarch64' >!< cpu)
  audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Azure Linux', cpu);

var pkgs = [
    {'reference':'bpftool-6.6.85.1-2.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'bpftool-6.6.85.1-2.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-6.6.85.1-2.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-6.6.85.1-2.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-debuginfo-6.6.85.1-2.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-debuginfo-6.6.85.1-2.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-devel-6.6.85.1-2.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-devel-6.6.85.1-2.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-docs-6.6.85.1-2.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-docs-6.6.85.1-2.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-accessibility-6.6.85.1-2.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-accessibility-6.6.85.1-2.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-gpu-6.6.85.1-2.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-gpu-6.6.85.1-2.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-intree-amdgpu-6.6.85.1-2.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-intree-amdgpu-6.6.85.1-2.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-sound-6.6.85.1-2.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-sound-6.6.85.1-2.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-tools-6.6.85.1-2.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-tools-6.6.85.1-2.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'python3-perf-6.6.85.1-2.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'python3-perf-6.6.85.1-2.azl3', 'cpu':'x86_64', 'release':'3.0', '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 = 'Azure Linux ' + 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, 'bpftool / kernel / kernel-debuginfo / kernel-devel / kernel-docs / etc');
}