Siemens SIMATIC S7-1500 TM MFP Improper Input Validation (CVE-2026-53263)

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

include('compat.inc');

if (description)
{
  script_id(506263);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/20");

  script_cve_id("CVE-2026-53263");

  script_name(english:"Siemens SIMATIC S7-1500 TM MFP Improper Input Validation (CVE-2026-53263)");

  script_set_attribute(attribute:"synopsis", value:
"The remote OT asset is affected by a vulnerability.");
  script_set_attribute(attribute:"description", value:
"In the Linux kernel, the following vulnerability has been resolved:

6lowpan: fix off-by-one in multicast context address compression

The second memcpy in lowpan_iphc_mcast_ctx_addr_compress() uses
&data[1] as destination and &ipaddr->s6_addr[11] as source, but
both should be offset by one: &data[2] and &ipaddr->s6_addr[12]
respectively.

This off-by-one has two consequences:
1. data[1] is overwritten with s6_addr[11], corrupting the RIID
   field in the compressed multicast address
2. data[5] is never written, so uninitialized kernel stack memory
   is transmitted over the network via lowpan_push_hc_data(),
   leaking kernel stack contents

The correct inline data layout must match what the decompression
function lowpan_uncompress_multicast_ctx_daddr() expects:
  data[0..1] = s6_addr[1..2]  (flags/scope + RIID)
  data[2..5] = s6_addr[12..15] (group ID)

Also zero-initialize the data array as a defensive measure against
similar bugs in the future.

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.");
  script_set_attribute(attribute:"see_also", value:"https://cert-portal.siemens.com/productcert/html/ssa-784472.html");
  script_set_attribute(attribute:"solution", value:
"Refer to the vendor advisory.");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-53263");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_cwe_id(20);

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/10/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/10/13");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/20");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:siemens:simatic_s7-1500_tm_mfp");
  script_set_attribute(attribute:"generated_plugin", value:"former");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Tenable.ot");

  script_copyright(english:"This script is Copyright (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("tenable_ot_api_integration.nasl");
  script_require_keys("Tenable.ot/Siemens");

  exit(0);
}


include('tenable_ot_cve_funcs.inc');

get_kb_item_or_exit('Tenable.ot/Siemens');

var asset = tenable_ot::assets::get(vendor:'Siemens');

var vuln_cpes = {
    "cpe:/o:siemens:simatic_s7-1500_tm_mfp" :
        {"versionEndIncluding" : "1.1.1", "versionStartIncluding" : "1.1.1", "family" : "S71500", "orderNumbers": ["6ES7558-1AA00-0AB0"]}
};

tenable_ot::cve::compare_and_report(asset:asset, cpes:vuln_cpes, severity:SECURITY_WARNING);