Linux Distros Unpatched Vulnerability : CVE-2026-80849

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

include('compat.inc');

if (description)
{
  script_id(343017);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/04");

  script_cve_id("CVE-2026-80849");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-80849");

  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.

  - net/tcp-ao: fix use-after-free of current_key on reconnect to another peer tcp_inbound_ao_hash() is called
    before bh_lock_sock_nested() is taken, with only rcu_read_lock() held. On the fast path for established
    sockets, if the rnext_keyid sent by the peer differs from current_key->sndid, the key the peer asked for
    is looked up and stored in current_key. The lookup is inside the RCU read side, but current_key outlives
    it. When the socket is disconnected and connect() is called again for another peer, tcp_ao_connect_init()
    unlinks every key that does not match the new peer and frees it with call_rcu(). If current_key points at
    such a key, it is cleared to NULL. The fast path reads sk_state only once on entry, so a softirq that got
    into it while the socket was still established can update current_key after that loop has already run. The
    update is inside the RCU read side, so it comes before the call_rcu() callback, and once the callback
    frees the key, current_key is left pointing at freed memory. The next transmission picks that pointer up
    in tcp_get_current_key(). tcp_ao_transmit_skb() then reads the traffic key from the freed object, which is
    the use-after-free. Wait for one grace period before unlinking, and only if a key is going to be removed.
    By the time tcp_connect() runs the socket is already in TCP_SYN_SENT, and TCP_AO_ESTABLISHED does not
    contain TCPF_SYN_SENT, so a softirq entering after the wait cannot reach the fast path, and the ones
    already in it have finished. The existing NULL handling in the loop is then enough. (CVE-2026-80849)

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-2026-80849");
  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-2026-80849");

  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');
}