Is CVE-2021-31337 actively exploited?

No active exploitation of CVE-2021-31337 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-31337 be exploited remotely?

Yes. CVE-2021-31337 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-31337?

CVE-2021-31337 has a CVSS score of 9.8 (CRITICAL).

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CRITICAL

CVE-2021-31337

CWE-306Published: June 28, 2021· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official 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).

NVD Source

Technical Analysis

CVE-2021-31337 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.