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)…

published 2021-06-08 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-18250

cvss: 7.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.0%; EPSS 1.0% chance of exploitation in 30 days, percentile 62%
public exploits: 0; none known

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.

Patch / fix

fixed in 20 links 1

siemens simatic_rf166c_firmware 1.3.2
siemens simatic_rf185c_firmware 1.3.2
siemens simatic_rf186c_firmware 1.3.2
siemens simatic_rf186ci_firmware 1.3.2
siemens simatic_rf188c_firmware 1.3.2
siemens simatic_rf188ci_firmware 1.3.2
siemens simatic_rf360r_firmware 2.0
siemens simatic_reader_rf610r_cmiit_firmware 4.0
siemens simatic_reader_rf610r_etsi_firmware 4.0
siemens simatic_reader_rf610r_fcc_firmware 4.0
siemens simatic_reader_rf615r_cmiit_firmware 4.0
siemens simatic_reader_rf615r_etsi_firmware 4.0
siemens simatic_reader_rf615r_fcc_firmware 4.0
siemens simatic_reader_rf650r_cmiit_firmware 4.0
siemens simatic_reader_rf650r_etsi_firmware 4.0
siemens simatic_reader_rf650r_fcc_firmware 4.0
siemens simatic_reader_rf650r_arib_firmware 4.0
siemens simatic_reader_rf680r_cmiit_firmware 4.0
siemens simatic_reader_rf680r_etsi_firmware 4.0
siemens simatic_reader_rf680r_fcc_firmware 4.0

cert-portal.siemens.com/productcert/pdf/ssa-787292.pdf advisory

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-21-159-13 updated 2025-05-06 cvss 7.5

Siemens SIMATIC RFID (Update B)

Siemens SIMATIC Reader RF610R CMIIT >V3.0, <V4.0 Siemens SIMATIC Reader RF610R ETSI >V3.0, <V4.0 Siemens SIMATIC Reader RF610R FCC >V3.0, <V4.0 Siemens SIMATIC Reader RF615R CMIIT >V3.0, <V4.0 Siemens SIMATIC Reader RF615R ETSI >V3.0, <V4.0 Siemens SIMATIC Reader RF615R FCC >V3.0, <V4.0

+12 more productsfewer

Siemens SIMATIC Reader RF650R ARIB >V3.0, <V4.0 Siemens SIMATIC Reader RF650R CMIIT >V3.0, <V4.0 Siemens SIMATIC Reader RF650R ETSI >V3.0, <V4.0 Siemens SIMATIC Reader RF650R FCC >V3.0, <V4.0 Siemens SIMATIC Reader RF680R ARIB >V3.0, <V4.0 Siemens SIMATIC Reader RF680R CMIIT >V3.0, <V4.0 Siemens SIMATIC Reader RF680R ETSI >V3.0, <V4.0 Siemens SIMATIC Reader RF680R FCC >V3.0, <V4.0 Siemens SIMATIC Reader RF685R ARIB >V3.0, <V4.0 Siemens SIMATIC Reader RF685R CMIIT >V3.0, <V4.0 Siemens SIMATIC Reader RF685R ETSI >V3.0, <V4.0 Siemens SIMATIC Reader RF685R FCC >V3.0, <V4.0

affected: fixed in V4.0, mitigation support.industry.siemens.com
Siemens SIMATIC RF166C >V1.1, <V1.3.2 Siemens SIMATIC RF185C >V1.1, <V1.3.2 Siemens SIMATIC RF186C >V1.1, <V1.3.2 Siemens SIMATIC RF186CI >V1.1, <V1.3.2 Siemens SIMATIC RF188C >V1.1, <V1.3.2 Siemens SIMATIC RF188CI >V1.1, <V1.3.2
affected: fixed in V1.3.2, mitigation support.industry.siemens.com
Siemens SIMATIC RF360R <V2.0
affected: fixed in V2.0, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Exploit prediction

0.99% chance of exploitation in the next 30 days, higher than 62% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

Siemens SIMATIC RF166C
Siemens SIMATIC RF185C
Siemens SIMATIC RF186C
Siemens SIMATIC RF186CI
Siemens SIMATIC RF188C
Siemens SIMATIC RF188CI
Siemens SIMATIC RF360R
Siemens SIMATIC Reader RF610R CMIIT
Siemens SIMATIC Reader RF610R ETSI
Siemens SIMATIC Reader RF610R FCC
Siemens SIMATIC Reader RF615R CMIIT
Siemens SIMATIC Reader RF615R ETSI
Siemens SIMATIC Reader RF615R FCC
Siemens SIMATIC Reader RF650R ARIB
Siemens SIMATIC Reader RF650R CMIIT
Siemens SIMATIC Reader RF650R ETSI
Siemens SIMATIC Reader RF650R FCC
Siemens SIMATIC Reader RF680R ARIB
Siemens SIMATIC Reader RF680R CMIIT
Siemens SIMATIC Reader RF680R ETSI
Siemens SIMATIC Reader RF680R FCC
Siemens SIMATIC Reader RF685R ARIB
Siemens SIMATIC Reader RF685R CMIIT
Siemens SIMATIC Reader RF685R ETSI
Siemens SIMATIC Reader RF685R FCC

Classification

Weakness

CWE-400 Uncontrolled Resource Consumption

References

cert-portal.siemens.com /productcert/pdf/ssa-787292.pdf
mitigation, patch, vendor-advisory

Sources

CVE List CVE-2021-31340
NVD CVE-2021-31340

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary