Linux Distros Unpatched Vulnerability : CVE-2026-89646

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

include('compat.inc');

if (description)
{
  script_id(345426);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/12");

  script_cve_id("CVE-2026-89646");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-89646");

  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.

  - ceph: fix leaked inode reference on writeback abort at umount ceph_dirty_folio() takes a wrbuffer claim on
    each newly dirtied folio: it bumps i_wrbuffer_ref (taking an ihold() on the 0->1 transition) and attaches
    the snap_context to folio->private. That claim is released only by ceph_put_wrbuffer_cap_refs(), which for
    a submitted write runs from writepages_finish(). In ceph_submit_write(), if
    ceph_inc_osd_stopping_blocker() fails -- which happens during umount -- the request is aborted before
    submission: the already-collected folios are only redirtied and unlocked, so writepages_finish() never
    runs and the claim is leaked. redirty_page_for_writepage() -> folio_redirty_for_writepage() ->
    filemap_dirty_folio() sets PG_dirty directly and does not go through ->dirty_folio, so ceph_dirty_folio()
    is not re-entered to rebalance it. Because every subsequent writeback also fails the osd_stopping_blocker,
    i_wrbuffer_ref never returns to 0, the ihold() is never dropped, and the inode cannot be evicted: VFS:
    Busy inodes after unmount of ceph kernel BUG at fs/super.c:650! Release the orphaned claim in the abort
    path before redirtying, via ceph_undo_wrbuffer_claim(): detach the snap_context, drop the wrbuffer
    reference (letting i_wrbuffer_ref reach 0 and iput() the inode), and drop the snap_context reference --
    i.e. do what writepages_finish() would have done for these never-submitted folios. Only the locked_pages
    entries are undone; folios still in the fbatch were never dirty-cleared by this call
    (folio_clear_dirty_for_io() is the ownership-transfer point, and a successful move NULLs the fbatch slot),
    so they hold no claim this call owns. (CVE-2026-89646)

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-2026-89646");
  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:L/AC:L/Au:N/C:P/I:N/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:U/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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-2026-89646");

  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:"2026/09/11");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/12");

  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-7.1.13+deb14-alpha-generic"},
          {"reference": "linux-base-7.1.13+deb14-alpha-smp"},
          {"reference": "linux-base-7.1.13+deb14-amd64"},
          {"reference": "linux-base-7.1.13+deb14-arm64"},
          {"reference": "linux-base-7.1.13+deb14-arm64-16k"},
          {"reference": "linux-base-7.1.13+deb14-armmp"},
          {"reference": "linux-base-7.1.13+deb14-armmp-lpae"},
          {"reference": "linux-base-7.1.13+deb14-cloud-amd64"},
          {"reference": "linux-base-7.1.13+deb14-cloud-arm64"},
          {"reference": "linux-base-7.1.13+deb14-loong64"},
          {"reference": "linux-base-7.1.13+deb14-m68k"},
          {"reference": "linux-base-7.1.13+deb14-parisc"},
          {"reference": "linux-base-7.1.13+deb14-parisc64"},
          {"reference": "linux-base-7.1.13+deb14-powerpc"},
          {"reference": "linux-base-7.1.13+deb14-powerpc-smp"},
          {"reference": "linux-base-7.1.13+deb14-powerpc64"},
          {"reference": "linux-base-7.1.13+deb14-powerpc64-64k"},
          {"reference": "linux-base-7.1.13+deb14-powerpc64le"},
          {"reference": "linux-base-7.1.13+deb14-powerpc64le-64k"},
          {"reference": "linux-base-7.1.13+deb14-riscv64"},
          {"reference": "linux-base-7.1.13+deb14-rt-amd64"},
          {"reference": "linux-base-7.1.13+deb14-rt-arm64"},
          {"reference": "linux-base-7.1.13+deb14-s390x"},
          {"reference": "linux-base-7.1.13+deb14-sh7751r"},
          {"reference": "linux-base-7.1.13+deb14-sparc64"},
          {"reference": "linux-base-7.1.13+deb14-sparc64-smp"}
        ]
      }
    ]
  }
};

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');
}