CVE-2021-31337

Name: CVE-2021-31337
Creator: NVD / NIST
Published: 2021-06-28T13:15:20.84+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 1.68%

Last modified Jun 17, 2026

CVE-2021-31337 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. The Telnet service of the SIMATIC HMI Comfort Panels system component in affected products does not require authentication, which may allow a remote attacker to gain access to the device if the service is enabled. Telnet is disabled by default on the SINAMICS Medium Voltage Products (SINAMICS SL150: All versions, SINAMICS SM150: All versions, SINAMICS SM150i: All versions).. EPSS estimates a 1.68% chance of exploitation in the next 30 days.

Description

The Telnet service of the SIMATIC HMI Comfort Panels system component in affected products does not require authentication, which may allow a remote attacker to gain access to the device if the service is enabled. Telnet is disabled by default on the SINAMICS Medium Voltage Products (SINAMICS SL150: All versions, SINAMICS SM150: All versions, SINAMICS SM150i: All versions).

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

1.68%

74.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-306

Affected Software

Vendor	Product	Versions
Siemens	Sinamics Sl150 Firmware	All versions
Siemens	Sinamics Sm150 Firmware	All versions
Siemens	Sinamics Sm150i Firmware	All versions

References

https://us-cert.cisa.gov/ics/advisories/icsa-21-131-04Not Applicable, Third Party Advisory, US Government Resource
https://us-cert.cisa.gov/ics/advisories/icsa-21-131-04Not Applicable, Third Party Advisory, US Government Resource

Timeline

Published: Jun 28, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-31337?

How severe is CVE-2021-31337?

CVE-2021-31337 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 1.68% probability of exploitation in the next 30 days.

How do I fix CVE-2021-31337?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-31337?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST