Linux Distros Unpatched Vulnerability : CVE-2026-80537

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

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  script_cve_id("CVE-2026-80537");

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"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.

  - xfs: fix off-by-one in rtrefcount btree root level validation xfs_rtrefcountbt_compute_maxlevels() sets
    mp->m_rtrefc_maxlevels = min(d_maxlevels, r_maxlevels) + 1; where the trailing + 1 already accounts for
    the inode-root level, so the deepest valid on-disk root level is m_rtrefc_maxlevels - 1 and a cursor must
    satisfy bc_nlevels <= bc_maxlevels (= m_rtrefc_maxlevels). The two on-disk validation paths,
    xfs_rtrefcountbt_verify() and xfs_iformat_rtrefcount(), check the root level with > instead of >=, so
    a crafted rtreflink (metadir + realtime + reflink) image whose /rtgroups/N.refcount inode has bb_level ==
    m_rtrefc_maxlevels is accepted on mount. xfs_rtrefcountbt_init_cursor() then sets bc_nlevels = bb_level +
    1, exceeding bc_maxlevels by one. Since the xfs_rtrefcountbt_cur slab object is sized for exactly
    bc_maxlevels entries, the first btree op on such a cursor indexes bc_levels[m_rtrefc_maxlevels] past the
    end of the object. This is reached by the first rtrefcount cursor built after mount, via log/CoW recovery
    (xfs_reflink_recover_cow() during xfs_mountfs()) or an FS_IOC_GETFSMAP over the realtime device. Reject a
    root level equal to m_rtrefc_maxlevels, matching the >= form already used by the sibling data-device
    refcount/rmap verifiers and the in-memory rtrmap verifier. BUG: KASAN: slab-out-of-bounds in
    xfs_btree_lookup (fs/xfs/libxfs/xfs_btree.c:2101) Write of size 2 at addr ffff888018391658 by task
    exploit/144 xfs_btree_lookup (fs/xfs/libxfs/xfs_btree.c:2101) xfs_btree_query_range
    (fs/xfs/libxfs/xfs_btree.c:5308) xfs_refcount_recover_cow_leftovers (fs/xfs/libxfs/xfs_refcount.c:2113)
    xfs_reflink_recover_cow (fs/xfs/xfs_reflink.c:1085) xlog_recover_finish (fs/xfs/xfs_log_recover.c:3551)
    xfs_mountfs (fs/xfs/xfs_mount.c:1158) xfs_fs_fill_super (fs/xfs/xfs_super.c:1940) get_tree_bdev_flags
    (fs/super.c:1634) vfs_get_tree (fs/super.c:1694) path_mount (fs/namespace.c:4161) __x64_sys_mount
    (fs/namespace.c:4367) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) The buggy address
    belongs to the cache xfs_rtrefcountbt_cur of size 216 The buggy address is located 8 bytes to the right of
    allocated 216-byte region [ffff888018391578, ffff888018391650) Kernel panic - not syncing: Fatal exception
    (CVE-2026-80537)

Note that Nessus relies on the presence of the package as reported by the vendor.");
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  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-80537");
  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:C/I:C/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:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
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  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", "Host/OS/Red Hat Enterprise Linux-10");

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}

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")) && empty_or_null(get_one_kb_item("Host/RedHat/rpm-list"))) 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-7.1.8+deb14.1-alpha-generic"},
          {"reference": "linux-base-7.1.8+deb14.1-alpha-smp"},
          {"reference": "linux-base-7.1.8+deb14.1-amd64"},
          {"reference": "linux-base-7.1.8+deb14.1-arm64"},
          {"reference": "linux-base-7.1.8+deb14.1-arm64-16k"},
          {"reference": "linux-base-7.1.8+deb14.1-armmp"},
          {"reference": "linux-base-7.1.8+deb14.1-armmp-lpae"},
          {"reference": "linux-base-7.1.8+deb14.1-cloud-amd64"},
          {"reference": "linux-base-7.1.8+deb14.1-cloud-arm64"},
          {"reference": "linux-base-7.1.8+deb14.1-loong64"},
          {"reference": "linux-base-7.1.8+deb14.1-m68k"},
          {"reference": "linux-base-7.1.8+deb14.1-parisc"},
          {"reference": "linux-base-7.1.8+deb14.1-parisc64"},
          {"reference": "linux-base-7.1.8+deb14.1-powerpc"},
          {"reference": "linux-base-7.1.8+deb14.1-powerpc-smp"},
          {"reference": "linux-base-7.1.8+deb14.1-powerpc64"},
          {"reference": "linux-base-7.1.8+deb14.1-powerpc64-64k"},
          {"reference": "linux-base-7.1.8+deb14.1-powerpc64le"},
          {"reference": "linux-base-7.1.8+deb14.1-powerpc64le-64k"},
          {"reference": "linux-base-7.1.8+deb14.1-riscv64"},
          {"reference": "linux-base-7.1.8+deb14.1-rt-amd64"},
          {"reference": "linux-base-7.1.8+deb14.1-rt-arm64"},
          {"reference": "linux-base-7.1.8+deb14.1-s390x"},
          {"reference": "linux-base-7.1.8+deb14.1-sh7751r"},
          {"reference": "linux-base-7.1.8+deb14.1-sparc64"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-10": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "10",
        "pkgs": [
          {"reference": "kernel"},
          {"reference": "kernel-64k"},
          {"reference": "kernel-64k-core"},
          {"reference": "kernel-64k-debug"},
          {"reference": "kernel-64k-debug-core"},
          {"reference": "kernel-64k-debug-devel"},
          {"reference": "kernel-64k-debug-devel-matched"},
          {"reference": "kernel-64k-debug-modules"},
          {"reference": "kernel-64k-debug-modules-core"},
          {"reference": "kernel-64k-debug-modules-extra"},
          {"reference": "kernel-64k-devel"},
          {"reference": "kernel-64k-devel-matched"},
          {"reference": "kernel-64k-modules"},
          {"reference": "kernel-64k-modules-core"},
          {"reference": "kernel-64k-modules-extra"},
          {"reference": "kernel-abi-stablelists"},
          {"reference": "kernel-core"},
          {"reference": "kernel-debug"},
          {"reference": "kernel-debug-core"},
          {"reference": "kernel-debug-devel"},
          {"reference": "kernel-debug-devel-matched"},
          {"reference": "kernel-debug-modules"},
          {"reference": "kernel-debug-modules-core"},
          {"reference": "kernel-debug-modules-extra"},
          {"reference": "kernel-debug-uki-virt"},
          {"reference": "kernel-devel"},
          {"reference": "kernel-devel-matched"},
          {"reference": "kernel-doc"},
          {"reference": "kernel-modules"},
          {"reference": "kernel-modules-core"},
          {"reference": "kernel-modules-extra"},
          {"reference": "kernel-modules-extra-matched"},
          {"reference": "kernel-rt"},
          {"reference": "kernel-rt-64k"},
          {"reference": "kernel-rt-64k-core"},
          {"reference": "kernel-rt-64k-debug"},
          {"reference": "kernel-rt-64k-debug-core"},
          {"reference": "kernel-rt-64k-debug-devel"},
          {"reference": "kernel-rt-64k-debug-modules"},
          {"reference": "kernel-rt-64k-debug-modules-core"},
          {"reference": "kernel-rt-64k-debug-modules-extra"},
          {"reference": "kernel-rt-64k-devel"},
          {"reference": "kernel-rt-64k-modules"},
          {"reference": "kernel-rt-64k-modules-core"},
          {"reference": "kernel-rt-64k-modules-extra"},
          {"reference": "kernel-rt-core"},
          {"reference": "kernel-rt-debug"},
          {"reference": "kernel-rt-debug-core"},
          {"reference": "kernel-rt-debug-devel"},
          {"reference": "kernel-rt-debug-kvm"},
          {"reference": "kernel-rt-debug-modules"},
          {"reference": "kernel-rt-debug-modules-core"},
          {"reference": "kernel-rt-debug-modules-extra"},
          {"reference": "kernel-rt-devel"},
          {"reference": "kernel-rt-kvm"},
          {"reference": "kernel-rt-modules"},
          {"reference": "kernel-rt-modules-core"},
          {"reference": "kernel-rt-modules-extra"},
          {"reference": "kernel-tools"},
          {"reference": "kernel-tools-libs"},
          {"reference": "kernel-tools-libs-devel"},
          {"reference": "kernel-uki-virt"},
          {"reference": "kernel-uki-virt-addons"},
          {"reference": "kernel-zfcpdump"},
          {"reference": "kernel-zfcpdump-core"},
          {"reference": "kernel-zfcpdump-devel"},
          {"reference": "kernel-zfcpdump-devel-matched"},
          {"reference": "kernel-zfcpdump-modules"},
          {"reference": "kernel-zfcpdump-modules-core"},
          {"reference": "kernel-zfcpdump-modules-extra"},
          {"reference": "libperf"},
          {"reference": "perf"},
          {"reference": "python3-perf"},
          {"reference": "rtla"},
          {"reference": "rv"}
        ]
      }
    ]
  }
};

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_HOLE,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}