CVE-2021-37185

A vulnerability has been identified in SIMATIC Drive Controller family (All versions >= V2.9.2 < V2.9.4), SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants) (All versions >= V21.9 < V21.9.4), SIMATIC S7-1200 CPU family (incl. SIPLUS variants) (All versions >= V4.5.0 < V4.5.2), SIMATIC S7-1500 CPU family (incl. related ET200 CPUs and SIPLUS variants) (All versions >= V2.9.2 < V2.9.4), SIMATIC S7-1500 Software Controller (All versions >= V21.9 < V21.9.4), SIMATIC S7-PLCSIM Advanced (All versions >= V4.0 < V4.0 SP1), SIPLUS TIM 1531 IRC (All versions < V2.3.6), TIM 1531 IRC (All versions < V2.3.6). An unauthenticated attacker could cause a denial-of-service condition in a PLC when sending specially prepared packets over port 102/tcp. A restart of the affected device is needed to restore normal operations.

Published: 2022-02-09 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-37185 is rated Moderate Risk (60.5/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.01%). EPSS rose +1.31% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-37185

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-18 0.70% 2.01% +1.31%
2 2025-11-21 1.43% 0.70% -0.73%
3 2025-11-18 — 1.43% —

Full EPSS history (13 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-37185

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
7.1 2.0 HIGH
AV:N/AC:M/Au:N/C:N/I:N/A:C Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:C)
Complete availability impact.
 8.6 6.9 [email protected]

Weakness enumeration for CVE-2021-37185

Affected software / configurations for CVE-2021-37185

Vendor Product Version Raw CPE
siemens simatic_drive_controller_cpu_1504d_tf_firmware < 2.9.4 cpe:2.3:o:siemens:simatic_drive_controller_cpu_1504d_tf_firmware:*:*:*:*:*:*:*:*
siemens simatic_drive_controller_cpu_1507d_tf_firmware < 2.9.4 cpe:2.3:o:siemens:simatic_drive_controller_cpu_1507d_tf_firmware:*:*:*:*:*:*:*:*
siemens simatic_et_200sp_open_controller_cpu_1515sp_pc2_firmware — cpe:2.3:o:siemens:simatic_et_200sp_open_controller_cpu_1515sp_pc2_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-plcsim_advanced_firmware < 4.0 cpe:2.3:o:siemens:simatic_s7-plcsim_advanced_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-plcsim_advanced_firmware 4.0 cpe:2.3:o:siemens:simatic_s7-plcsim_advanced_firmware:4.0:-:*:*:*:*:*:*
siemens tim_1531_irc_firmware >= 2.2 cpe:2.3:o:siemens:tim_1531_irc_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_software_controller — cpe:2.3:a:siemens:simatic_s7-1500_software_controller:*:*:*:*:*:*:*:*
siemens simatic_s7-1200_cpu_1211c_firmware >= 4.5.0, < 4.5.2 cpe:2.3:o:siemens:simatic_s7-1200_cpu_1211c_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1200_cpu_1212c_firmware >= 4.5.0, < 4.5.2 cpe:2.3:o:siemens:simatic_s7-1200_cpu_1212c_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1200_cpu_1212fc_firmware >= 4.5.0, < 4.5.2 cpe:2.3:o:siemens:simatic_s7-1200_cpu_1212fc_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1200_cpu_1214fc_firmware >= 4.5.0, < 4.5.2 cpe:2.3:o:siemens:simatic_s7-1200_cpu_1214fc_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1200_cpu_1214c_firmware >= 4.5.0, < 4.5.2 cpe:2.3:o:siemens:simatic_s7-1200_cpu_1214c_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1200_cpu_1215fc_firmware >= 4.5.0, < 4.5.2 cpe:2.3:o:siemens:simatic_s7-1200_cpu_1215fc_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1200_cpu_1215c_firmware >= 4.5.0, < 4.5.2 cpe:2.3:o:siemens:simatic_s7-1200_cpu_1215c_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1200_cpu_1217c_firmware >= 4.5.0, < 4.5.2 cpe:2.3:o:siemens:simatic_s7-1200_cpu_1217c_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1510sp-1_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1510sp-1_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1510sp_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1510sp_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1511-1_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1511-1_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1511c-1_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1511c-1_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1511f-1_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1511f-1_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1511t-1_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1511t-1_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1511tf-1_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1511tf-1_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1512c-1_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1512c-1_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1512sp-1_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1512sp-1_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1512spf-1_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1512spf-1_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1513-1_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1513-1_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1513f-1_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1513f-1_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1513r-1_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1513r-1_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_cpu_1513prof-2_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_cpu_1513prof-2_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_cpu_1513pro-2_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_cpu_1513pro-2_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1515-2_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1515-2_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1515f-2_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1515f-2_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1515r-2_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1515r-2_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1515t-2_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1515t-2_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1515tf-2_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1515tf-2_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1516pro_f_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1516pro_f_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1516pro-2_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1516pro-2_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1516-3_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1516-3_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1516f-3_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1516f-3_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1516t-3_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1516t-3_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1516tf-3_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1516tf-3_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1517-3_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1517-3_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1517f-3_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1517f-3_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1517tf-3_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1517tf-3_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1518-4_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1518-4_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1518f-4_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1518f-4_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1518hf-4_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1518hf-4_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1518t-4_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1518t-4_firmware:*:*:*:*:*:*:*:*
siemens simatic_s7-1500_cpu_1518tf-4_firmware >= 2.9.2, < 2.9.4 cpe:2.3:o:siemens:simatic_s7-1500_cpu_1518tf-4_firmware:*:*:*:*:*:*:*:*

References for CVE-2021-37185

cvelogic Threat Intelligence