How severe is CVE-2021-27386?

CVE-2021-27386 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-27386 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (76th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27386?

CVE-2021-27386 primarily affects Siemens Simatic Wincc Runtime Advanced. In total, 119 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-27386?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-27386 published?

CVE-2021-27386 was published on 2021-05-12 and last updated on 2026-06-17.

CVE-2021-27386

CVE-2021-27386 is a high-severity vulnerability in Siemens Simatic Wincc Runtime Advanced with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-401.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (76th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-401
Affected product: Siemens Simatic Wincc Runtime Advanced
Published: 2021-05-12
Last modified: 2026-06-17

Description

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), SINAMICS GH150 (All versions), SINAMICS GL150 (with option X30) (All versions), SINAMICS GM150 (with option X30) (All versions), SINAMICS SH150 (All versions), SINAMICS SL150 (All versions), SINAMICS SM120 (All versions), SINAMICS SM150 (All versions), SINAMICS SM150i (All versions). SmartVNC has a heap allocation leak vulnerability in the device layout handler on client side, which could result in a Denial-of-Service condition.

Frequently asked questions

What is CVE-2021-27386?: 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), SINAMICS GH150 (All versions), SINAMICS GL150 (with option X30) (All versions), SINAMICS GM150 (with option X30) (All versions), SINAMICS SH150 (All versions), SINAMICS SL150 (All versions), SINAMICS SM120 (All versions), SINAMICS SM150 (All versions), SINAMICS SM150i (All versions). SmartVNC has a heap allocation leak vulnerability in the device layout handler on client side, which could result in a Denial-of-Service condition.
How severe is CVE-2021-27386?: CVE-2021-27386 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-27386 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (76th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27386?: CVE-2021-27386 primarily affects Siemens Simatic Wincc Runtime Advanced. In total, 119 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-27386?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-27386 published?: CVE-2021-27386 was published on 2021-05-12 and last updated on 2026-06-17.

References

Affected products (119)

cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:*:*:*:*:*:*:*:*
cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:16:-:*:*:*:*:*:*
cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:16:update1:*:*:*:*:*:*
cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:16:update2:*:*:*:*:*:*
cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:16:update3:*:*:*:*:*:*
cpe:2.3:o:siemens:sinamics_sh150_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:sinamics_sm150i_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:sinamics_gh150_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:sinamics_gl150_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:sinamics_gm150_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:sinamics_sl150_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:sinamics_sm120_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:sinamics_sm150_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:16:-:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:16:update1:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:16:update2:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_7\"_firmware:16:update3:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:16:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:16:-:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:16:update1:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:16:update2:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_outdoor_panels_15\"_firmware:16:update3:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:16:-:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:16:update1:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:16:update2:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_panels_4\"_firmware:16:update3:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:16:-:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:16:update1:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:16:update2:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_comfort_panels_22\"_firmware:16:update3:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp400f_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp400f_firmware:16:-:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp400f_firmware:16:update1:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp400f_firmware:16:update2:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp400f_firmware:16:update3:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_hmi_ktp_mobile_panels_ktp700_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Siemens Simatic Wincc Runtime Advanced

CVE-2021-27384 — Critical (CVSS 9.8): A vulnerability has been identified in SIMATIC HMI Comfort Outdoor Panels V15 7\" & 15\" (incl. SIPLUS variants) (All…
CVE-2021-27385 — High (CVSS 7.5): A vulnerability has been identified in SIMATIC HMI Comfort Outdoor Panels V15 7\" & 15\" (incl. SIPLUS variants) (All…
CVE-2021-27383 — High (CVSS 7.5): A vulnerability has been identified in SIMATIC HMI Comfort Outdoor Panels V15 7\" & 15\" (incl. SIPLUS variants) (All…
CVE-2021-25662 — High (CVSS 7.5): A vulnerability has been identified in SIMATIC HMI Comfort Outdoor Panels V15 7\" & 15\" (incl. SIPLUS variants) (All…
CVE-2021-25661 — High (CVSS 7.5): A vulnerability has been identified in SIMATIC HMI Comfort Outdoor Panels V15 7\" & 15\" (incl. SIPLUS variants) (All…
CVE-2021-25660 — High (CVSS 7.5): A vulnerability has been identified in SIMATIC HMI Comfort Outdoor Panels V15 7\" & 15\" (incl. SIPLUS variants) (All…

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