CVE-2021-37186

MEDIUM

Siemens LOGO! CMR2020/CMR2040 < 2.2 & SIMATIC RTU3010C/RTU3030C/RTU3031C/RTU3041C < 4.0.9 - Predictable TCP ISN

Title source: llm

Description

A vulnerability has been identified in LOGO! CMR2020 (All versions < V2.2), LOGO! CMR2040 (All versions < V2.2), SIMATIC RTU3010C (All versions < V4.0.9), SIMATIC RTU3030C (All versions < V4.0.9), SIMATIC RTU3031C (All versions < V4.0.9), SIMATIC RTU3041C (All versions < V4.0.9). The underlying TCP/IP stack does not properly calculate the random numbers used as ISN (Initial Sequence Numbers). An adjacent attacker with network access to the LAN interface could interfere with traffic, spoof the connection and gain access to sensitive information.

References (1)

Core 1

Core References

Patch, Vendor Advisory x_refsource_misc

https://cert-portal.siemens.com/productcert/pdf/ssa-316383.pdf

Scores

CVSS v3 5.4

EPSS 0.0034

EPSS Percentile 26.1%

Attack Vector ADJACENT_NETWORK

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Details

CWE

CWE-330

Status published

Products (6)

siemens/logo\!_cmr2020_firmware < 2.2

siemens/logo\!_cmr2040_firmware < 2.2

siemens/simatic_rtu3010c_firmware < 4.0.9

siemens/simatic_rtu3030c_firmware < 4.0.9

siemens/simatic_rtu3031c_firmware < 4.0.9

siemens/simatic_rtu3041c_firmware < 4.0.9

Published Sep 14, 2021

Tracked Since Feb 18, 2026