Siemens RUGGEDCOM RST2428P Improper Input Validation (CVE-2026-23111)

high Tenable OT Security Plugin ID 505388

Synopsis

The remote OT asset is affected by a vulnerability.

Description

In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate() nft_map_catchall_activate() has an inverted element activity check compared to its non-catchall counterpart nft_mapelem_activate() and compared to what is logically required. nft_map_catchall_activate() is called from the abort path to re-activate catchall map elements that were deactivated during a failed transaction. It should skip elements that are already active (they don't need re-activation) and process elements that are inactive (they need to be restored). Instead, the current code does the opposite: it skips inactive elements and processes active ones.
Compare the non-catchall activate callback, which is correct:
nft_mapelem_activate(): if (nft_set_elem_active(ext, iter->genmask)) return 0; /* skip active, process inactive
*/ With the buggy catchall version: nft_map_catchall_activate():
if (!nft_set_elem_active(ext, genmask)) continue; /* skip inactive, process active */ The consequence is that when a DELSET operation is aborted, nft_setelem_data_activate() is never called for the catchall element. For NFT_GOTO verdict elements, this means nft_data_hold() is never called to restore the chain->use reference count. Each abort cycle permanently decrements chain->use. Once chain->use reaches zero, DELCHAIN succeeds and frees the chain while catchall verdict elements still reference it, resulting in a use- after-free. This is exploitable for local privilege escalation from an unprivileged user via user namespaces + nftables on distributions that enable CONFIG_USER_NS and CONFIG_NF_TABLES. Fix by removing the negation so the check matches nft_mapelem_activate(): skip active elements, process inactive ones.

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: 505388

File Name: tenable_ot_siemens_CVE-2026-23111.nasl

Version: 1.1

Type: Remote

Family: Tenable.ot

Published: 6/18/2026

Updated: 6/18/2026

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: High

Score: 8.4

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:ruggedcom_rst2428p_firmware

Required KB Items: Tenable.ot/Siemens

Exploit Ease: No known exploits are available

Patch Publication Date: 6/2/2026

Vulnerability Publication Date: 2/13/2026

Reference Information

CVE: CVE-2026-23111

CWE: 20

Detections

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