Linux Distros Unpatched Vulnerability : CVE-2026-80850

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

include('compat.inc');

if (description)
{
  script_id(342949);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/04");

  script_cve_id("CVE-2026-80850");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-80850");

  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.

  - tcp: fix AO info use-after-free in tcp_ao_connect_init() tcp_v4_connect() adds a SYN-SENT socket to the
    ehash before calling tcp_connect(). If TCP-AO is configured, tcp_connect() first verifies that a key
    matches the peer and the bound device's current L3 master. tcp_ao_connect_init() later resolves the L3
    master again and removes keys which do not match it. The socket lock does not stabilize the bound device's
    VRF membership. Detaching the device from its VRF between the initial validation and the L3-master
    calculation in tcp_ao_connect_init() can therefore make the validation succeed while initialization
    observes the default L3 domain and removes the only key. The subsequent AO lookup then fails, so the no-
    key path clears tp->ao_info and frees it directly. The receive path can find the socket in the ehash and
    load tp->ao_info under RCU before acquiring the socket lock. A reader which loaded the old pointer can
    thus continue into tcp_inbound_ao_hash() after the direct free. The issue was found during a static audit
    of TCP-AO object lifetime. An unprivileged reproducer in self-created user and network namespaces raced
    connect() with detaching a veth from its VRF while sending TCP-AO segments. It triggered the same KASAN
    report on two fresh boots: BUG: KASAN: slab-use-after-free in tcp_inbound_ao_hash+0x585/0x19f0 Write of
    size 8 at addr ffff88800bf88128 by task tcp_ao_vrf_race/232 Call Trace: tcp_inbound_ao_hash+0x585/0x19f0
    tcp_inbound_hash+0x677/0xa80 tcp_v4_rcv+0x1c3e/0x3ab0 Allocated by task 235: tcp_ao_alloc_info+0x43/0xf0
    tcp_ao_add_cmd+0xdf7/0x13b0 do_tcp_setsockopt+0x168c/0x2640 Freed by task 235: kfree+0x1b8/0x550
    tcp_connect+0x252/0x4f00 tcp_v4_connect+0x1114/0x1720 The bad address is 40 bytes inside the freed
    128-byte object, matching the tcp_ao_info counters.key_not_found field. The two runs used 1000 attempts
    each, reached the no-key path 366 and 411 times, and produced one and two KASAN reports respectively. With
    this change, the same reproducer reached the no-key path 366 times in 1000 attempts without a KASAN report
    or oops. Use tcp_ao_destroy_sock() for the no-key path. It unpublishes the AO info, updates the socket
    memory and static-key accounting, and defers the free until after an RCU grace period. Also drop the
    WARN_ON_ONCE() and its stale comment. The VRF detach race makes the no-key state reachable during normal
    operation, so it is a handled condition rather than an impossible assertion. On panic_on_warn kernels the
    WARN would turn this handled race into a kernel panic. (CVE-2026-80850)

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-2026-80850");
  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-2026-80850");

  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:"2026/09/04");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/04");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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-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-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-7.1.12+deb14-alpha-generic"},
          {"reference": "linux-base-7.1.12+deb14-alpha-smp"},
          {"reference": "linux-base-7.1.12+deb14-amd64"},
          {"reference": "linux-base-7.1.12+deb14-arm64"},
          {"reference": "linux-base-7.1.12+deb14-arm64-16k"},
          {"reference": "linux-base-7.1.12+deb14-armmp"},
          {"reference": "linux-base-7.1.12+deb14-armmp-lpae"},
          {"reference": "linux-base-7.1.12+deb14-cloud-amd64"},
          {"reference": "linux-base-7.1.12+deb14-cloud-arm64"},
          {"reference": "linux-base-7.1.12+deb14-loong64"},
          {"reference": "linux-base-7.1.12+deb14-m68k"},
          {"reference": "linux-base-7.1.12+deb14-parisc"},
          {"reference": "linux-base-7.1.12+deb14-parisc64"},
          {"reference": "linux-base-7.1.12+deb14-powerpc"},
          {"reference": "linux-base-7.1.12+deb14-powerpc-smp"},
          {"reference": "linux-base-7.1.12+deb14-powerpc64"},
          {"reference": "linux-base-7.1.12+deb14-powerpc64-64k"},
          {"reference": "linux-base-7.1.12+deb14-powerpc64le"},
          {"reference": "linux-base-7.1.12+deb14-powerpc64le-64k"},
          {"reference": "linux-base-7.1.12+deb14-riscv64"},
          {"reference": "linux-base-7.1.12+deb14-rt-amd64"},
          {"reference": "linux-base-7.1.12+deb14-rt-arm64"},
          {"reference": "linux-base-7.1.12+deb14-s390x"},
          {"reference": "linux-base-7.1.12+deb14-sh7751r"},
          {"reference": "linux-base-7.1.12+deb14-sparc64"},
          {"reference": "linux-base-7.1.12+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-6.12.94+deb13-4kc-malta"},
          {"reference": "linux-headers-6.12.94+deb13-5kc-malta"},
          {"reference": "linux-headers-6.12.94+deb13-alpha-generic"},
          {"reference": "linux-headers-6.12.94+deb13-alpha-smp"},
          {"reference": "linux-headers-6.12.94+deb13-amd64"},
          {"reference": "linux-headers-6.12.94+deb13-arm64"},
          {"reference": "linux-headers-6.12.94+deb13-arm64-16k"},
          {"reference": "linux-headers-6.12.94+deb13-armmp"},
          {"reference": "linux-headers-6.12.94+deb13-armmp-lpae"},
          {"reference": "linux-headers-6.12.94+deb13-cloud-amd64"},
          {"reference": "linux-headers-6.12.94+deb13-cloud-arm64"},
          {"reference": "linux-headers-6.12.94+deb13-common"},
          {"reference": "linux-headers-6.12.94+deb13-common-rt"},
          {"reference": "linux-headers-6.12.94+deb13-loong64"},
          {"reference": "linux-headers-6.12.94+deb13-loongson-3"},
          {"reference": "linux-headers-6.12.94+deb13-m68k"},
          {"reference": "linux-headers-6.12.94+deb13-mips32r2eb"},
          {"reference": "linux-headers-6.12.94+deb13-mips32r2el"},
          {"reference": "linux-headers-6.12.94+deb13-mips64r2eb"},
          {"reference": "linux-headers-6.12.94+deb13-mips64r2el"}
        ]
      }
    ]
  }
};

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');
}