EulerOS 2.0 SP12 : xorg-x11-server (EulerOS-SA-2026-3320)

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

include('compat.inc');

if (description)
{
  script_id(343657);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/08");

  script_cve_id(
    "CVE-2026-50256",
    "CVE-2026-50257",
    "CVE-2026-50258",
    "CVE-2026-50259",
    "CVE-2026-50260",
    "CVE-2026-50261",
    "CVE-2026-50264",
    "CVE-2026-55999"
  );

  script_name(english:"EulerOS 2.0 SP12 : xorg-x11-server (EulerOS-SA-2026-3320)");

  script_set_attribute(attribute:"synopsis", value:
"The remote EulerOS host is missing multiple security updates.");
  script_set_attribute(attribute:"description", value:
"According to the versions of the xorg-x11-server packages installed, the EulerOS installation on the remote host is
affected by the following vulnerabilities :

    A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple
    stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-
    canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and
    trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash
    the server, or for privilege escalation if the X server runs as root.(CVE-2026-50258)

    A use-after-free flaw was found in the X.Org X server and Xwayland in FreeCounter(). A client that sets up
    multiple SyncCounters and awaits on those triggers can trigger a use-after-free when destroying those
    counters via a second client connection. This may be used to crash the server, or for privilege escalation
    if the X server runs as root.(CVE-2026-50260)

    A use-after-free flaw was found in the X.Org X server and Xwayland in SyncChangeCounter(). A client that
    sets up multiple SyncCounters can trigger a use-after-free when destroying those counters via a second
    client connection while changing those counters. This may be used to crash the server, or for privilege
    escalation if the X server runs as root.(CVE-2026-50261)

    Local attackers with a X connection able to provide PCX fonts to the X
    server xorg-server before 21.2.24 and xwayland before 24.1.13 could
    cause a heap buffer overflow via SetFont due to missing glyph boundary checks.(CVE-2026-55999)

    An out-of-bounds write flaw was found in the X.Org X server and Xwayland in
    DRIGetBuffers/DRIGetBuffersWithFormat. A client that requests multiple DRI2BufferBackLeft attachments and
    one DRI2BufferFrontLeft can trigger an out-of-bounds heap write. This may be used to crash the server, or
    for privilege escalation if the X server runs as root.(CVE-2026-50264)

    A use-after-free flaw was found in the X.Org X server and Xwayland in miSyncDestroyFence(). A client that
    sets up multiple fence triggers can trigger a use-after-free function pointer call. An attacker would
    connect to the X server to set up a fence and await that fence, then a second X connection destroys the
    fence, causing the use-after-free. This may be used to crash the server, or for privilege escalation if
    the X server runs as root.(CVE-2026-50257)

    A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. _XkbSetMapChecks()
    declares a fixed-size stack buffer mapWidths[256] indexed by key type index. The helper function
    CheckKeyTypes() writes to this buffer at a client-controlled offset, allowing a stack buffer overflow.
    This may be used to crash the server, or for privilege escalation if the X server runs as
    root.(CVE-2026-50259)

    A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. A mismatch between the X
    server and the libXfont2 library's maximum font name length can cause a stack buffer overflow during font
    alias resolution. The server allocates a 256 byte stack buffer but libXfont2's alias target name length is
    1024 bytes. A font alias name between 257 and 1023 bytes causes the X server to copy that name into the
    undersized stack buffer without further checks. This may be used to crash the server, or for privilege
    escalation if the X server runs as root.(CVE-2026-50256)

Tenable has extracted the preceding description block directly from the EulerOS xorg-x11-server security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  # https://developer.huaweicloud.com/ict/en/site-euleros/euleros/security-advisories/EulerOS-SA-2026-3320
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?fdb0d34d");
  script_set_attribute(attribute:"solution", value:
"Update the affected xorg-x11-server 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-2026-55999");

  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:"2026/06/01");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/08");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/08");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:xorg-x11-server");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:xorg-x11-server-common");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:xorg-x11-server-help");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:huawei:euleros:2.0");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Huawei 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/cpu", "Host/EulerOS/release", "Host/EulerOS/rpm-list", "Host/EulerOS/sp");
  script_exclude_keys("Host/EulerOS/uvp_version");

  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/EulerOS/release");
if (isnull(_release) || _release !~ "^EulerOS") audit(AUDIT_OS_NOT, "EulerOS");
var uvp = get_kb_item("Host/EulerOS/uvp_version");
if (_release !~ "^EulerOS release 2\.0(\D|$)") audit(AUDIT_OS_NOT, "EulerOS 2.0 SP12");

var sp = get_kb_item("Host/EulerOS/sp");
if (isnull(sp) || sp !~ "^(12)$") audit(AUDIT_OS_NOT, "EulerOS 2.0 SP12");

if (!empty_or_null(uvp)) audit(AUDIT_OS_NOT, "EulerOS 2.0 SP12", "EulerOS UVP " + uvp);

if (!get_kb_item("Host/EulerOS/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$" && "aarch64" >!< cpu && "x86" >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "EulerOS", cpu);
if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$" && "x86" >!< cpu) audit(AUDIT_ARCH_NOT, "i686 / x86_64", cpu);

var flag = 0;

var pkgs = [
  "xorg-x11-server-1.20.11-13.h18.eulerosv2r12",
  "xorg-x11-server-common-1.20.11-13.h18.eulerosv2r12",
  "xorg-x11-server-help-1.20.11-13.h18.eulerosv2r12"
];

foreach (var pkg in pkgs)
  if (rpm_check(release:"EulerOS-2.0", sp:"12", reference:pkg)) 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, "xorg-x11-server");
}