Siemens SIMATIC S7-1500 Missing Cryptographic Step (CVE-2025-69418)

medium Tenable OT Security Plugin ID 505147

Synopsis

The remote OT asset is affected by a vulnerability.

Description

Issue summary: When using the low-level OCB API directly with AES-NI or other hardware-accelerated code paths, inputs whose length is not a multiple of 16 bytes can leave the final partial block unencrypted and unauthenticated. Impact summary: The trailing 1-15 bytes of a message may be exposed in cleartext on encryption and are not covered by the authentication tag, allowing an attacker to read or tamper with those bytes without detection. The low- level OCB encrypt and decrypt routines in the hardware- accelerated stream path process full 16-byte blocks but do not advance the input/output pointers. The subsequent tail-handling code then operates on the original base pointers, effectively reprocessing the beginning of the buffer while leaving the actual trailing bytes unprocessed. The authentication checksum also excludes the true tail bytes. However, typical OpenSSL consumers using EVP are not affected because the higher-level EVP and provider OCB implementations split inputs so that full blocks and trailing partial blocks are processed in separate calls, avoiding the problematic code path. Additionally, TLS does not use OCB ciphersuites. The vulnerability only affects applications that call the low-level CRYPTO_ocb128_encrypt() or CRYPTO_ocb128_decrypt() functions directly with non-block-aligned lengths in a single call on hardware-accelerated builds. For these reasons the issue was assessed as Low severity. The FIPS modules in 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 and 3.0 are not affected by this issue, as OCB mode is not a FIPS-approved algorithm. OpenSSL 3.6, 3.5, 3.4, 3.3, 3.0 and 1.1.1 are vulnerable to this issue. OpenSSL 1.0.2 is not affected by this issue.

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: Medium

ID: 505147

File Name: tenable_ot_siemens_CVE-2025-69418.nasl

Version: 1.1

Type: remote

Family: Tenable.ot

Published: 2/13/2026

Updated: 2/13/2026

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Medium

Score: 4.0

CVSS v3

Risk Factor: Medium

Base Score: 4

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

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: 4/9/2024

Vulnerability Publication Date: 4/9/2024

Reference Information

CVE: CVE-2025-69418

CWE: 325

Detections

Analytics