Linux Distros Unpatched Vulnerability : CVE-2026-64262

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

include('compat.inc');

if (description)
{
  script_id(329889);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/25");

  script_cve_id("CVE-2026-64262");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-64262");

  script_set_attribute(attribute:"synopsis", value:
"The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be
patched.");
  script_set_attribute(attribute:"description", value:
"The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied
patch available.

  - fuse-uring: end fuse_req on io-uring cancel task work When io_uring delivers task work with tw.cancel set
    (PF_EXITING, PF_KTHREAD fallback, or percpu_ref_is_dying on the ring context), fuse_uring_send_in_task()
    takes the cancel branch, assigns -ECANCELED, and falls through to fuse_uring_send(). That path only flips
    the entry to FRRS_USERSPACE and completes the io_uring cmd; it never discharges the ring entry's owning
    reference to the fuse_req that fuse_uring_add_req_to_ring_ent() handed it at dispatch time.
    fuse_uring_send_in_task() tw.cancel == true err = -ECANCELED fuse_uring_send(ent, cmd, err, issue_flags)
    ent->state = FRRS_USERSPACE list_move(&ent->list, &queue->ent_in_userspace) ent->cmd = NULL
    io_uring_cmd_done(-ECANCELED) /* ent->fuse_req still set, req still hashed */ The fuse_req stays linked on
    fpq->processing[hash] and fuse_request_end() is never invoked. The originating syscall thread blocks in
    D-state in request_wait_answer() until fuse_abort_conn() runs, which can be the entire connection
    lifetime. For FR_BACKGROUND requests fc->num_background is never decremented either, so repeated cancels
    inflate the counter until max_background is hit and all later background ops stall. tw.cancel does not
    imply a connection abort (e.g. a single io_uring worker thread exits while the fuse connection stays up),
    so this cannot be left for fuse_abort_conn() to clean up. Ending the req but still routing the entry
    through fuse_uring_send() is not enough: that leaves a req-less entry on ent_in_userspace, and
    ent_list_request_expired() dereferences ent->fuse_req unconditionally on the head of that list, which
    would then NULL-deref. Fix the cancel branch to release the entry directly. Remove it from the queue,
    complete the io_uring cmd, end the fuse_req, free the entry, and drop its queue_refs (waking the teardown
    waiter if it was the last). (CVE-2026-64262)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-64262");
  script_set_attribute(attribute:"solution", value:
"There is no known solution at this time.");
  script_set_attribute(attribute:"agent", value:"unix");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:U/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-64262");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_set_attribute(attribute:"vendor_unpatched", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/07/25");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/25");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:14.0");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:linux");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

  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", "set_linux_os_id.nasl");
  script_require_keys("Host/cpu", "Host/local_checks_enabled", "global_settings/vendor_unpatched", "Host/OS/identifier");
  script_require_ports("Host/OS/Debian Linux-14");

  exit(0);
}

if (!get_kb_item("global_settings/vendor_unpatched")) exit(0, "Unpatched Vulnerabilities Detection not active.");
if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (empty_or_null(get_one_kb_item("Host/Debian/dpkg-l"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Debian Linux-14": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14",
        "pkgs": [
          {"reference": "bpftool"},
          {"reference": "hyperv-daemons"},
          {"reference": "intel-sdsi"},
          {"reference": "libcpupower-dev"},
          {"reference": "libcpupower1"},
          {"reference": "linux-base-7.1.3+deb14-alpha-generic"},
          {"reference": "linux-base-7.1.3+deb14-alpha-smp"},
          {"reference": "linux-base-7.1.3+deb14-amd64"},
          {"reference": "linux-base-7.1.3+deb14-arm64"},
          {"reference": "linux-base-7.1.3+deb14-arm64-16k"},
          {"reference": "linux-base-7.1.3+deb14-armmp"},
          {"reference": "linux-base-7.1.3+deb14-armmp-lpae"},
          {"reference": "linux-base-7.1.3+deb14-cloud-amd64"},
          {"reference": "linux-base-7.1.3+deb14-cloud-arm64"},
          {"reference": "linux-base-7.1.3+deb14-loong64"},
          {"reference": "linux-base-7.1.3+deb14-m68k"},
          {"reference": "linux-base-7.1.3+deb14-parisc"},
          {"reference": "linux-base-7.1.3+deb14-parisc64"},
          {"reference": "linux-base-7.1.3+deb14-powerpc"},
          {"reference": "linux-base-7.1.3+deb14-powerpc-smp"},
          {"reference": "linux-base-7.1.3+deb14-powerpc64"},
          {"reference": "linux-base-7.1.3+deb14-powerpc64-64k"},
          {"reference": "linux-base-7.1.3+deb14-powerpc64le"},
          {"reference": "linux-base-7.1.3+deb14-powerpc64le-64k"},
          {"reference": "linux-base-7.1.3+deb14-riscv64"},
          {"reference": "linux-base-7.1.3+deb14-rt-amd64"},
          {"reference": "linux-base-7.1.3+deb14-rt-arm64"},
          {"reference": "linux-base-7.1.3+deb14-s390x"},
          {"reference": "linux-base-7.1.3+deb14-sh7751r"},
          {"reference": "linux-base-7.1.3+deb14-sparc64"},
          {"reference": "linux-base-7.1.3+deb14-sparc64-smp"},
          {"reference": "linux-base-7.1.3+deb14-test"}
        ]
      }
    ]
  }
};

var distro_constraints_values = linux_unpatched::get_distro_constraints(distro_constraints_arr:distro_constraints_array);
if (empty_or_null(distro_constraints_values)) audit(AUDIT_HOST_NOT, 'affected');

var third_party_support = get_kb_item('Host/OS/extended-third-party');
if (!empty_or_null(third_party_support)) {
    var third_party_vendors = distro_constraints_values['third_party'];
    if (!empty_or_null(third_party_vendors)) {
        var vendor;
        foreach vendor (third_party_vendors) {
            if (vendor == third_party_support) exit(0, 'A third party management patch is available for this vulnerability from ' + vendor + '.\n');
        }
    }
}

var report = linux_unpatched::check_unpatched_constraints(distro_constraints_values:distro_constraints_values);

if (!empty_or_null(report))
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}