What’s Vulnerable › Vulnerabilities

CVE-2021-31337

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-06-28 · updated 2026-06-17
• Weakness: CWE-306

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).

Affected products

• 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-21-131-04
• https://us-cert.cisa.gov/ics/advisories/icsa-21-131-04

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