Siemens SIMATIC S7-1500 TM MFP Improper Input Validation (CVE-2026-31630)

high Tenable OT Security Plugin ID 506439

Synopsis

The remote OT asset is affected by a vulnerability.

Description

In the Linux kernel, the following vulnerability has been resolved:

rxrpc: proc: size address buffers for %pISpc output

The AF_RXRPC procfs helpers format local and remote socket addresses into fixed 50-byte stack buffers with '%pISpc'.

That is too small for the longest current-tree IPv6-with-port form the formatter can produce. In lib/vsprintf.c, the compressed IPv6 path uses a dotted-quad tail not only for v4mapped addresses, but also for ISATAP addresses via ipv6_addr_is_isatap().

As a result, a case such as

[ffff:ffff:ffff:ffff:0:5efe:255.255.255.255]:65535

is possible with the current formatter. That is 50 visible characters, so 51 bytes including the trailing NUL, which does not fit in the existing char[50] buffers used by net/rxrpc/proc.c.

Size the buffers from the formatter's maximum textual form and switch the call sites to scnprintf().

Changes since v1:
- correct the changelog to cite the actual maximum current-tree case explicitly
- frame the proof around the ISATAP formatting path instead of the earlier mapped-v4 example

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.

Solution

Refer to the vendor advisory.

Plugin Details

Severity: High

ID: 506439

File Name: tenable_ot_siemens_CVE-2026-31630.nasl

Version: 1.1

Type: Remote

Family: Tenable.ot

Published: 10/20/2026

Updated: 10/20/2026

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: High

Score: 7.6

Percentile: 98.21

CVSS v3

Risk Factor: High

Base Score: 7.8

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

Vulnerability Information

CPE: cpe:/o:siemens:simatic_s7-1500_tm_mfp

Required KB Items: Tenable.ot/Siemens

Exploit Ease: No known exploits are available

Patch Publication Date: 10/13/2026

Vulnerability Publication Date: 10/13/2026

Reference Information

CVE: CVE-2026-31630

CWE: 20

Detections

Analytics