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Vulnerability record · CVE-2021-31340 · published 8 June 2021

CVE-2021-31340: Siemens simatic rf166c firmware uncontrolled resource consumption vulnerability

Siemens · Simatic Rf166c Firmware

A vulnerability has been identified in SIMATIC RF166C (All versions > V1.1 and < V1.3.2), SIMATIC RF185C (All versions > V1.1 and < V1.3.2), SIMATIC RF186C (All versions > V1.1 and < V1.3.2), SIMATIC RF186CI (All versions > V1.1 and < V1.3.2), SIMATIC RF188C (All versions > V1.1 and < V1.3.2), SIMATIC RF188CI (All versions > V1.1 and < V1.3.2), SIMATIC RF360R (All versions < V2.0), SIMATIC Reader RF610R CMIIT (All versions > V3.0 < V4.0), SIMATIC Reader RF610R ETSI (All versions > V3.0 < V4.0), SIMATIC Reader RF610R FCC (All versions > V3.0 < V4.0), SIMATIC Reader RF615R CMIIT (All versions > V3.0 < V4.0), SIMATIC Reader RF615R ETSI (All versions > V3.0 < V4.0), SIMATIC Reader RF615R FCC (All versions > V3.0 < V4.0), SIMATIC Reader RF650R ARIB (All versions > V3.0 < V4.0), SIMATIC Reader RF650R CMIIT (All versions > V3.0 < V4.0), SIMATIC Reader RF650R ETSI (All versions > V3.0 < V4.0), SIMATIC Reader RF650R FCC (All versions > V3.0 < V4.0), SIMATIC Reader RF680R ARIB (All versions > V3.0 < V4.0), SIMATIC Reader RF680R CMIIT (All versions > V3.0 < V4.0), SIMATIC Reader RF680R ETSI (All versions > V3.0 < V4.0), SIMATIC Reader RF680R FCC (All versions > V3.0 < V4.0), SIMATIC Reader RF685R ARIB (All versions > V3.0 < V4.0), SIMATIC Reader RF685R CMIIT (All versions > V3.0 < V4.0), SIMATIC Reader RF685R ETSI (All versions > V3.0 < V4.0), SIMATIC Reader RF685R FCC (All versions > V3.0 < V4.0). Affected devices do not properly handle large numbers of incoming connections. An attacker may leverage this to cause a Denial-of-Service situation.

7.5 CVSS 3.1 High EPSS 0.99% · top 38.8% CWE-400 · Uncontrolled resource consumption
7.5CVSS 3.1 base score, v2 5.0
0.99%EPSS exploitation probability, 30 days
NoNot in CISA KEV
25Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

A vulnerability has been identified in SIMATIC RF166C (All versions > V1.1 and < V1.3.2), SIMATIC RF185C (All versions > V1.1 and < V1.3.2), SIMATIC RF186C (All versions > V1.1 and < V1.3.2), SIMATIC RF186CI (All versions > V1.1 and < V1.3.2), SIMATIC RF188C (All versions > V1.1 and < V1.3.2), SIMATIC RF188CI (All versions > V1.1 and < V1.3.2), SIMATIC RF360R (All versions < V2.0), SIMATIC Reader RF610R CMIIT (All versions > V3.0 < V4.0), SIMATIC Reader RF610R ETSI (All versions > V3.0 < V4.0), SIMATIC Reader RF610R FCC (All versions > V3.0 < V4.0), SIMATIC Reader RF615R CMIIT (All versions > V3.0 < V4.0), SIMATIC Reader RF615R ETSI (All versions > V3.0 < V4.0), SIMATIC Reader RF615R FCC (All versions > V3.0 < V4.0), SIMATIC Reader RF650R ARIB (All versions > V3.0 < V4.0), SIMATIC Reader RF650R CMIIT (All versions > V3.0 < V4.0), SIMATIC Reader RF650R ETSI (All versions > V3.0 < V4.0), SIMATIC Reader RF650R FCC (All versions > V3.0 < V4.0), SIMATIC Reader RF680R ARIB (All versions > V3.0 < V4.0), SIMATIC Reader RF680R CMIIT (All versions > V3.0 < V4.0), SIMATIC Reader RF680R ETSI (All versions > V3.0 < V4.0), SIMATIC Reader RF680R FCC (All versions > V3.0 < V4.0), SIMATIC Reader RF685R ARIB (All versions > V3.0 < V4.0), SIMATIC Reader RF685R CMIIT (All versions > V3.0 < V4.0), SIMATIC Reader RF685R ETSI (All versions > V3.0 < V4.0), SIMATIC Reader RF685R FCC (All versions > V3.0 < V4.0). Affected devices do not properly handle large numbers of incoming connections. An attacker may leverage this to cause a Denial-of-Service situation.

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

Affected products

25 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://cert-portal.siemens.com/productcert/pdf/ssa-787292.pdf MitigationPatchVendor Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-787292.pdf MitigationPatchVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-31340), CISA KEV, FIRST EPSS (scores of 2026-10-04). This page is refreshed as NVD updates the record.