Amazon Linux 2 : gstreamer1-plugins-bad-free, --advisory ALAS2-2026-3833 (ALAS-2026-3833)

#%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-2026-3833.
##

include('compat.inc');

if (description)
{
  script_id(332044);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/04");

  script_cve_id("CVE-2026-12892", "CVE-2026-59691", "CVE-2026-59692");

  script_name(english:"Amazon Linux 2 : gstreamer1-plugins-bad-free, --advisory ALAS2-2026-3833 (ALAS-2026-3833)");

  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 gstreamer1-plugins-bad-free installed on the remote host is prior to 1.18.4-5. It is, therefore, affected
by multiple vulnerabilities as referenced in the ALAS2-2026-3833 advisory.

    A flaw was found in GStreamer's gst-plugins-bad package. When processing a specially crafted H.264 video
    file containing malformed MVC or SVC extension slice NAL units, a 1-byte heap out-of-bounds read can occur
    during parsing. This happens when the parser attempts to check slice boundary information without first
    verifying that the NAL unit contains enough data beyond the extension header. An attacker could exploit
    this by tricking a user into opening a malicious H.264 video file, potentially causing the application to
    crash or leak a single byte of heap memory. (CVE-2026-12892)

    A heap buffer overflow vulnerability was found in GStreamer's rfbsrc plugin. When a client connects to a
    malicious RFB/VNC server that advertises a 16bpp framebuffer and sends Hextile-encoded updates, the
    Hextile background fill path writes 32-bit pixel values into a buffer allocated for 16-bit pixels. This
    type mismatch causes an out-of-bounds heap write that can lead to denial of service (process crash) and
    potential memory corruption. (CVE-2026-59691)

    A stack buffer overflow vulnerability was found in GStreamer's DTLS plugin. During a DTLS handshake, the
    peer certificate Subject Distinguished Name is printed into a fixed-size 2048-byte stack buffer without
    bounds checking. A remote unauthenticated attacker can send a certificate with an oversized Subject DN
    that exceeds the buffer, causing a stack buffer overflow and process crash, resulting in denial of
    service. (CVE-2026-59692)

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/ALAS2-2026-3833.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/faqs.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-12892.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-59691.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-59692.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update gstreamer1-plugins-bad-free' or
  or 'yum update --advisory ALAS2-2026-3833' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/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-2026-59691");

  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:"2026/06/23");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/04");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/04");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:gstreamer1-plugins-bad-free");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:gstreamer1-plugins-bad-free-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:gstreamer1-plugins-bad-free-devel");
  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) 2026 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("rpm2.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':'gstreamer1-plugins-bad-free-1.18.4-5.amzn2.0.7', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'gstreamer1-plugins-bad-free-1.18.4-5.amzn2.0.7', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'gstreamer1-plugins-bad-free-debuginfo-1.18.4-5.amzn2.0.7', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'gstreamer1-plugins-bad-free-debuginfo-1.18.4-5.amzn2.0.7', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'gstreamer1-plugins-bad-free-devel-1.18.4-5.amzn2.0.7', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'gstreamer1-plugins-bad-free-devel-1.18.4-5.amzn2.0.7', '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_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, "gstreamer1-plugins-bad-free / gstreamer1-plugins-bad-free-debuginfo / gstreamer1-plugins-bad-free-devel");
}