CVE-2021-25660

A vulnerability has been identified in SIMATIC HMI Comfort Outdoor Panels V15 7\" & 15\" (incl. SIPLUS variants) (All versions < V15.1 Update 6), SIMATIC HMI Comfort Outdoor Panels V16 7\" & 15\" (incl. SIPLUS variants) (All versions < V16 Update 4), SIMATIC HMI Comfort Panels V15 4\" - 22\" (incl. SIPLUS variants) (All versions < V15.1 Update 6), SIMATIC HMI Comfort Panels V16 4\" - 22\" (incl. SIPLUS variants) (All versions < V16 Update 4), SIMATIC HMI KTP Mobile Panels V15 KTP400F, KTP700, KTP700F, KTP900 and KTP900F (All versions < V15.1 Update 6), SIMATIC HMI KTP Mobile Panels V16 KTP400F, KTP700, KTP700F, KTP900 and KTP900F (All versions < V16 Update 4), SIMATIC WinCC Runtime Advanced V15 (All versions < V15.1 Update 6), SIMATIC WinCC Runtime Advanced V16 (All versions < V16 Update 4). SmartVNC has an out-of-bounds memory access vulnerability that could be triggered on the server side when sending data from the client, which could result in a Denial-of-Service condition.

Published: 2021-05-12 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-25660 is rated Moderate Risk (50.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.96%). 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-2021-25660

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 2026-06-15 0.46% 0.96% +0.50%
2 2025-03-30 0.72% 0.46% -0.26%
3 2025-03-29 — 0.72% —

Full EPSS history (11 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-25660

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 134c704f-9b21-4f2e-91b3-4a467353bcc0
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-25660

GitHub Security Advisory for CVE-2021-25660

GHSA-rmq3-87p9-r2fp · Severity: high — A vulnerability has been identified in SIMATIC HMI Comfort Outdoor Panels 7\" & 15\" (incl....

Affected software / configurations for CVE-2021-25660

Vendor Product Version Raw CPE
siemens simatic_hmi_comfort_outdoor_panels_7\"_firmware < 16 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:*:*:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_7\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:16:-:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_7\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:16:update1:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_7\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:16:update2:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_7\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:16:update3:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_15\"_firmware < 16 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:*:*:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_15\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:16:*:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_15\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:16:-:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_15\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:16:update1:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_15\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:16:update2:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_15\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:16:update3:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_4\"_firmware < 16 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:*:*:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_4\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:16:-:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_4\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:16:update1:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_4\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:16:update2:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_4\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:16:update3:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_22\"_firmware < 16 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:*:*:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_22\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:16:-:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_22\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:16:update1:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_22\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:16:update2:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_22\"_firmware 16 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:16:update3:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp400f_firmware < 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp400f_firmware:*:*:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp400f_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp400f_firmware:16:-:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp400f_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp400f_firmware:16:update1:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp400f_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp400f_firmware:16:update2:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp400f_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp400f_firmware:16:update3:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp700_firmware < 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp700_firmware:*:*:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp700_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp700_firmware:16:-:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp700_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp700_firmware:16:update1:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp700_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp700_firmware:16:update2:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp700_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp700_firmware:16:update3:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp700f_firmware < 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp700f_firmware:*:*:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp700f_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp700f_firmware:16:-:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp700f_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp700f_firmware:16:update1:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp700f_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp700f_firmware:16:update2:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp700f_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp700f_firmware:16:update3:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp900_firmware < 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp900_firmware:*:*:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp900_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp900_firmware:16:-:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp900_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp900_firmware:16:update1:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp900_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp900_firmware:16:update2:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp900_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp900_firmware:16:update3:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp900f_firmware < 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp900f_firmware:*:*:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp900f_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp900f_firmware:16:-:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp900f_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp900f_firmware:16:update1:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp900f_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp900f_firmware:16:update2:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp900f_firmware 16 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp900f_firmware:16:update3:*:*:*:*:*:*
siemens simatic_wincc_runtime_advanced < 16 cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:*:*:*:*:*:*:*:*
siemens simatic_wincc_runtime_advanced 16 cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:16:-:*:*:*:*:*:*
siemens simatic_wincc_runtime_advanced 16 cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:16:update1:*:*:*:*:*:*
siemens simatic_wincc_runtime_advanced 16 cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:16:update2:*:*:*:*:*:*
siemens simatic_wincc_runtime_advanced 16 cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:16:update3:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_7\"_firmware < 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:*:*:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_7\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:15.1:-:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_7\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:15.1:update1:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_7\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:15.1:update2:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_7\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:15.1:update3:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_7\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:15.1:update4:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_7\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:15.1:update5:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_15\"_firmware < 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:*:*:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_15\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:15.1:-:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_15\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:15.1:update1:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_15\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:15.1:update2:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_15\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:15.1:update3:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_15\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:15.1:update4:*:*:*:*:*:*
siemens simatic_hmi_comfort_outdoor_panels_15\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:15.1:update5:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_4\"_firmware < 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:*:*:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_4\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:15.1:-:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_4\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:15.1:update1:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_4\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:15.1:update2:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_4\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:15.1:update3:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_4\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:15.1:update4:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_4\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:15.1:update5:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_22\"_firmware < 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:*:*:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_22\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:15.1:-:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_22\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:15.1:update1:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_22\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:15.1:update2:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_22\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:15.1:update3:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_22\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:15.1:update4:*:*:*:*:*:*
siemens simatic_hmi_comfort_panels_22\"_firmware 15.1 cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:15.1:update5:*:*:*:*:*:*
siemens simatic_hmi_ktp_mobile_panels_ktp400f_firmware < 15.1 cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp400f_firmware:*:*:*:*:*:*:*:*

References for CVE-2021-25660

cvelogic Threat Intelligence