Linux Distros Unpatched Vulnerability : CVE-2026-64593

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

include('compat.inc');

if (description)
{
  script_id(333078);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/06");

  script_cve_id("CVE-2026-64593");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-64593");

  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.

  - btrfs: do not trim a device which is not writeable [BUG] There is a bug report that btrfs/242 can randomly
    fail with the following NULL pointer dereference: run fstests btrfs/242 at 2026-06-01 10:25:08 BTRFS:
    device fsid d4d7f234-487c-4787-88e4-47a8b68c9874 devid 1 transid 9 /dev/sdc (8:32) scanned by mount
    (122609) BTRFS info (device sdc): first mount of filesystem d4d7f234-487c-4787-88e4-47a8b68c9874 BTRFS
    info (device sdc): using crc32c checksum algorithm BTRFS warning (device sdc): devid 2 uuid
    fbe72d72-3272-482d-80fb-ab88ed398192 is missing BTRFS warning (device sdc): devid 2 uuid
    fbe72d72-3272-482d-80fb-ab88ed398192 is missing BTRFS info (device sdc): allowing degraded mounts BTRFS
    info (device sdc): turning on async discard BTRFS info (device sdc): enabling free space tree Unable to
    handle kernel NULL pointer dereference at virtual address 0000000000000018 user pgtable: 4k pages, 48-bit
    VAs, pgdp=000000013fd6b000 CPU: 4 UID: 0 PID: 122625 Comm: fstrim Not tainted 7.0.10-2-default #1
    PREEMPT(full) openSUSE Tumbleweed e9a5f6b24978fba3bf015a992f865837fdfff3dd Hardware name: QEMU KVM Virtual
    Machine, BIOS edk2-20250812-19.fc42 08/12/2025 pstate: 01400005 (nzcv daif +PAN -UAO -TCO +DIT -SSBS
    BTYPE=--) pc : btrfs_trim_fs+0x34c/0xa00 [btrfs] lr : btrfs_trim_fs+0x1f0/0xa00 [btrfs] Call trace:
    btrfs_trim_fs+0x34c/0xa00 [btrfs f02c1d570ceea621c69d302ba75dd61868083840] (P)
    btrfs_ioctl_fitrim+0xe8/0x178 [btrfs f02c1d570ceea621c69d302ba75dd61868083840] btrfs_ioctl+0xdd4/0x2bd8
    [btrfs f02c1d570ceea621c69d302ba75dd61868083840] __arm64_sys_ioctl+0xac/0x108
    invoke_syscall.constprop.0+0x5c/0xd0 el0_svc_common.constprop.0+0x40/0xf0 do_el0_svc+0x24/0x40
    el0_svc+0x40/0x1d0 el0t_64_sync_handler+0xa0/0xe8 el0t_64_sync+0x1b0/0x1b8 Code: 17ffff83 f94017e0
    f9002be0 f9402ea0 (f9400c00) ---[ end trace 0000000000000000 ]--- Also the reporter is very kind to test
    the following ASSERT() added to btrfs_trim_free_extents_throttle(): ASSERT(device->bdev, devid=%llu
    path=%s dev_state=0x%lx\n, device->devid, btrfs_dev_name(device), device->dev_state); And it shows the
    following output: assertion failed: device->bdev, in extent-tree.c:6630 (devid=2 path=/dev/sdd
    dev_state=0x82) Which means the device->bdev is NULL, and the dev_state is BTRFS_DEV_STATE_IN_FS_METADATA
    | BTRFS_DEV_STATE_ITEM_FOUND, without BTRFS_DEV_STATE_WRITEABLE flag set. [CAUSE] The pc points to the
    following call chain: btrfs_trim_fs() |- btrfs_trim_free_extents() |- btrfs_trim_free_extents_throttle()
    |- bdev_max_discard_sectors(device->bdev) So the NULL pointer dereference is caused by device->bdev being
    NULL. This looks impossible by a quick glance, as just before calling btrfs_trim_free_extents_throttle(),
    we have skipped any device that has BTRFS_DEV_STATE_MISSING flag set. However in this particular case,
    there is a window where the missing device is later re-scanned, causing btrfs to remove the
    BTRFS_DEV_STATE_MISSING flag: btrfs_control_ioctl() |- btrfs_scan_one_device() |- device_list_add() |-
    rcu_assign_pointer(device->name, name); | This updates the missing device's path to the new good path. |
    |- clear_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state) This removes the BTRFS_DEV_STATE_MISSING flag.
    This allows the missing device to re-appear and clear the BTRFS_DEV_STATE_MISSING flag. However the device
    still does not have the BTRFS_DEV_STATE_WRITEABLE flag set, nor is its bdev pointer updated. The bdev
    pointer remains NULL, triggering the crash later. [FIX] This is a big de-synchronization between
    BTRFS_DEV_STATE_MISSING and device->bdev pointer, and shows a gap in btrfs's re-appearing-device handling.
    The proper handling of re-appearing device will need quite some extra work, which is out of the context of
    this small ---truncated--- (CVE-2026-64593)

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-2026-64593");
  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-2026-64593");

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

  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');
}