Linux Distros Unpatched Vulnerability : CVE-2026-89761

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

include('compat.inc');

if (description)
{
  script_id(345410);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/12");

  script_cve_id("CVE-2026-89761");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-89761");

  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.

  - apparmor: fix out-of-bounds write when null terminating a label vec aa_vec_unique() null terminates at
    vec[n - dups] when VEC_FLAG_TERMINATE is passed. If the components are all distinct no duplicates are
    dropped, dups is 0 and the terminator goes to vec[n], so the caller has to provide room for n + 1 entries.
    aa_label_strn_parse() sets up its vector with vec_setup(profile, vec, len, gfp) and then calls
    aa_vec_unique(vec, len, VEC_FLAG_TERMINATE), but vec_setup() does not reserve the terminator entry. Up to
    LOCAL_VEC_ENTRIES it uses the local array of LOCAL_VEC_ENTRIES pointers, above that it allocates exactly
    len pointers. The terminator therefore lands one entry past the end of the local array when len is
    LOCAL_VEC_ENTRIES, and one entry past the end of the allocation when len is larger. len comes from the
    number of //& separated components in the label name and label_count_strn_entries() does not bound it.
    An unprivileged task reaches the parse by writing to /proc/self/attr/apparmor/current or through
    lsm_set_self_attr(2), both of which go through do_setattr(), and the name is parsed before the
    change_profile permission is checked. The query_label() path behind the securityfs .access file, which is
    mode 0666, performs no permission check at all. Every component has to resolve to a loaded profile, so a
    system with policy loaded is required. The other two VEC_FLAG_TERMINATE users work on a label vec that
    aa_label_alloc() has already sized with + 1 for null terminator entry on vec. Reserve the same entry in
    vec_setup() and DEFINE_VEC(). Passing len + 1 from the caller instead would move len == LOCAL_VEC_ENTRIES
    out of the local array and into kzalloc(). (CVE-2026-89761)

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-2026-89761");
  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:N/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:N/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-2026-89761");

  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:12.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:13.0");
  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-12", "Host/OS/Debian Linux-13", "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-12": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "12",
        "pkgs": [
          {"reference": "btrfs-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "cdrom-core-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "ext4-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "fat-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "isofs-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "jfs-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "kernel-image-6.1.0-50-alpha-generic-di"},
          {"reference": "linux-doc"},
          {"reference": "linux-doc-6.1"},
          {"reference": "linux-headers-6.1.0"},
          {"reference": "linux-source"},
          {"reference": "linux-source-6.1"},
          {"reference": "linux-support-6.1.0"},
          {"reference": "loop-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "nic-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "nic-shared-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "nic-wireless-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "pata-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "ppp-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "scsi-core-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "scsi-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "scsi-nic-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "serial-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "usb-serial-modules-6.1.0-50-alpha-generic-di"},
          {"reference": "xfs-modules-6.1.0-50-alpha-generic-di"}
        ]
      }
    ]
  },
  "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"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "bpftool"},
          {"reference": "hyperv-daemons"},
          {"reference": "intel-sdsi"},
          {"reference": "libcpupower-dev"},
          {"reference": "libcpupower1"},
          {"reference": "linux-bpf-dev"},
          {"reference": "linux-config-6.12"},
          {"reference": "linux-cpupower"},
          {"reference": "linux-doc"},
          {"reference": "linux-doc-6.12"},
          {"reference": "linux-headers-4kc-malta"},
          {"reference": "linux-headers-5kc-malta"},
          {"reference": "linux-headers-6.12.107+deb13-4kc-malta"},
          {"reference": "linux-headers-6.12.107+deb13-5kc-malta"},
          {"reference": "linux-headers-6.12.107+deb13-alpha-generic"},
          {"reference": "linux-headers-6.12.107+deb13-alpha-smp"},
          {"reference": "linux-headers-6.12.107+deb13-amd64"},
          {"reference": "linux-headers-6.12.107+deb13-arm64"},
          {"reference": "linux-headers-6.12.107+deb13-arm64-16k"},
          {"reference": "linux-headers-6.12.107+deb13-armmp"},
          {"reference": "linux-headers-6.12.107+deb13-armmp-lpae"},
          {"reference": "linux-headers-6.12.107+deb13-cloud-amd64"},
          {"reference": "linux-headers-6.12.107+deb13-cloud-arm64"},
          {"reference": "linux-headers-6.12.107+deb13-common"},
          {"reference": "linux-headers-6.12.107+deb13-common-rt"},
          {"reference": "linux-headers-6.12.107+deb13-loong64"},
          {"reference": "linux-headers-6.12.107+deb13-loongson-3"},
          {"reference": "linux-headers-6.12.107+deb13-m68k"},
          {"reference": "linux-headers-6.12.107+deb13-mips32r2eb"},
          {"reference": "linux-headers-6.12.107+deb13-mips32r2el"},
          {"reference": "linux-headers-6.12.107+deb13-mips64r2eb"}
        ]
      }
    ]
  }
};

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');
}