Siemens SIMATIC S7-1500 Improper Locking (CVE-2025-39773)

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

include('compat.inc');

if (description)
{
  script_id(505167);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/02/17");

  script_cve_id("CVE-2025-39773");

  script_name(english:"Siemens SIMATIC S7-1500 Improper Locking (CVE-2025-39773)");

  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:
net: bridge: fix soft lockup in br_multicast_query_expired()    When
set multicast_query_interval to a large value, the local variable
'time' in br_multicast_send_query() may overflow. If the time is
smaller  than jiffies, the timer will expire immediately, and then
call mod_timer()  again, which creates a loop and may trigger the
following soft lockup  issue.      watchdog: BUG: soft lockup - CPU#1
stuck for 221s! [rb_consumer:66]    CPU: 1 UID: 0 PID: 66 Comm:
rb_consumer Not tainted 6.16.0+ #259 PREEMPT(none)    Call Trace:
<IRQ>     __netdev_alloc_skb+0x2e/0x3a0
br_ip6_multicast_alloc_query+0x212/0x1b70
__br_multicast_send_query+0x376/0xac0
br_multicast_send_query+0x299/0x510
br_multicast_query_expired.constprop.0+0x16d/0x1b0
call_timer_fn+0x3b/0x2a0     __run_timers+0x619/0x950
run_timer_softirq+0x11c/0x220     handle_softirqs+0x18e/0x560
__irq_exit_rcu+0x158/0x1a0     sysvec_apic_timer_interrupt+0x76/0x90
</IRQ>    This issue can be reproduced with:    ip link add br0 type
bridge    echo 1 > /sys/class/net/br0/bridge/multicast_querier    echo
0xffffffffffffffff >
/sys/class/net/br0/bridge/multicast_query_interval    ip link set dev
br0 up    The multicast_startup_query_interval can also cause this
issue. Similar to  the commit 99b40610956a (net: bridge: mcast: add
and enforce query  interval minimum), add check for the query
interval maximum to fix this  issue.

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-082556.html");
  script_set_attribute(attribute:"solution", value:
"Refer to the vendor advisory.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  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_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2025-39773");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_cwe_id(667);

  script_set_attribute(attribute:"vuln_publication_date", value:"2025/06/10");
  script_set_attribute(attribute:"patch_publication_date", value:"2025/06/10");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/02/16");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:siemens:simatic_s7-1500_cpu_firmware:3.1.5");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:siemens:siplus_s7-1500_cpu_firmware:3.1.5");
  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_cpu_firmware:3.1.5" :
        {"versionStartIncluding" : "3.1.5", "family" : "S71500", "orderNumbers" : ['6ES7518-4AX00-1AB0', '6ES7518-4FX00-1AC0', '6ES7518-4AX00-1AC0', '6ES7518-4FX00-1AB0']},
    "cpe:/o:siemens:siplus_s7-1500_cpu_firmware:3.1.5" :
        {"versionStartIncluding" : "3.1.5", "family" : "S71500", "orderNumbers" : ['6AG1518-4AX00-4AC0']}
};

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