Siemens SIMATIC NET CP 443-1 OPC UA Out-of-Bounds Read (CVE-2016-2518)

medium Tenable OT Security Plugin ID 501089


The remote OT asset is affected by a vulnerability.


The MATCH_ASSOC function in NTP before version 4.2.8p9 and 4.3.x before 4.3.92 allows remote attackers to cause an out-of-bounds reference via an addpeer request with a large hmode value.

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The following text was originally created by the Cybersecurity and Infrastructure Security Agency (CISA). The original can be found at

Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk:

- Deactivate NTP-based time synchronization of the device, if enabled. The feature is disabled by default.
- Configure an additional firewall to prevent communication to Port UDP/123 of an affected device.

As a general security measure, Siemens strongly recommends users protect network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends users configure the environment according to Siemens operational guidelines for industrial security, and follow the recommendations in the product manual.

Additional information on industrial security by Siemens can be found at:

For more information about this issue, please see Siemens security advisory SSA-211752

See Also

Plugin Details

Severity: Medium

ID: 501089

Version: 1.2

Type: remote

Family: Tenable.ot

Published: 5/2/2023

Updated: 7/24/2023

Supported Sensors: Nessus

Risk Information


Risk Factor: Low

Score: 1.4


Risk Factor: Medium

Base Score: 5

Temporal Score: 3.7

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS Score Source: CVE-2016-2518


Risk Factor: Medium

Base Score: 5.3

Temporal Score: 4.6

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:siemens:simatic_net_cp_443-1_opc_ua_firmware

Required KB Items: Tenable.ot/Siemens

Exploit Ease: No known exploits are available

Patch Publication Date: 1/30/2017

Vulnerability Publication Date: 1/30/2017

Reference Information

CVE: CVE-2016-2518

CWE: 125

DSA: DSA-3629

FEDORA: FEDORA-2016-5b2eb0bf9c, FEDORA-2016-ed8c6c0426


GLSA: GLSA-201607-15

RHSA: RHSA-2016:1141, RHSA-2016:1552

SuSE: SUSE-SU-2016:1278, SUSE-SU-2016:1291, SUSE-SU-2016:1471, SUSE-SU-2016:1568, SUSE-SU-2016:1912, SUSE-SU-2016:2094, openSUSE-SU-2016:1329, openSUSE-SU-2016:1423

USN: USN-3096-1