ICSA-21-131-12: Siemens SIMATIC SmartVNC HMI WinCC Products (Update B)
CISA advisory · released 2021-05-11
Source record Collected from CISA's CSAF advisory feed
- Distribution label in the document: TLP:WHITE
- Revision 4, 2025-05-06 (final)
CISA's summary
Summary: Multiple SmartVNC vulnerabilities in the affected products listed below could allow remote code execution and Denial-of-Service attacks under certain conditions. Siemens has released updates for the affected products and recommends to update to the latest version.
Products, as the advisory lists them
| Vendor | Product | Version |
|---|---|---|
| Siemens | SIMATIC HMI Comfort Outdoor Panels V15 7" & 15" (incl. SIPLUS variants) | <V15.1_Update_6 |
| Siemens | SIMATIC HMI Comfort Outdoor Panels V16 7" & 15" (incl. SIPLUS variants) | <V16_Update_4 |
| Siemens | SIMATIC HMI Comfort Panels V15 4" - 22" (incl. SIPLUS variants) | <V15.1_Update_6 |
| Siemens | SIMATIC HMI Comfort Panels V16 4" - 22" (incl. SIPLUS variants) | <V16_Update_4 |
| Siemens | SIMATIC HMI KTP Mobile Panels V15 KTP400F, KTP700, KTP700F, KTP900 and KTP900F | <V15.1_Update_6 |
| Siemens | SIMATIC HMI KTP Mobile Panels V16 KTP400F, KTP700, KTP700F, KTP900 and KTP900F | <V16_Update_4 |
| Siemens | SIMATIC WinCC Runtime Advanced V15 | <V15.1_Update_6 |
| Siemens | SIMATIC WinCC Runtime Advanced V16 | <V16_Update_4 |
DeSpy has not checked any unit, hardware revision or firmware.
Vulnerabilities in this advisory
- CVE-2021-25660 — CVE-2021-25660 · CWE-788
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.
- CVE-2021-25661 — CVE-2021-25661 · CWE-788
SmartVNC has an out-of-bounds memory access vulnerability that could be triggered on the client side when sending data from the server, which could result in a Denial-of-Service condition.
- CVE-2021-25662 — CVE-2021-25662 · CWE-755
SmartVNC client fails to handle an exception properly if the program execution process is modified after sending a packet from the server, which could result in a Denial-of-Service condition.
- CVE-2021-27383 — CVE-2021-27383 · CWE-770
SmartVNC has a heap allocation leak vulnerability in the server Tight encoder, which could result in a Denial-of-Service condition.
- CVE-2021-27384 — CVE-2021-27384 · CWE-788
SmartVNC has an out-of-bounds memory access vulnerability in the device layout handler, represented by a binary data stream on client side, which can potentially result in code execution.
- CVE-2021-27385 — CVE-2021-27385 · CWE-400
A remote attacker could send specially crafted packets to SmartVNC device layout handler on client side, which could influence the amount of resources consumed and result in a Denial-of-Service (infinite loop) condition.
- CVE-2021-27386 — CVE-2021-27386 · CWE-401
SmartVNC has a heap allocation leak vulnerability in the device layout handler on client side, which could result in a Denial-of-Service condition.
Acknowledgments, as the advisory lists them
- Siemens ProductCERT: reporting these vulnerabilities to CISA.
The advisory's legal notice
Siemens Security Advisories are subject to the terms and conditions contained in Siemens' underlying license terms or other applicable agreements previously agreed to with Siemens (hereinafter "License Terms"). To the extent applicable to information, software or documentation made available in or through a Siemens Security Advisory, the Terms of Use of Siemens' Global Website (https://www.siemens.com/terms_of_use, hereinafter "Terms of Use"), in particular Sections 8-10 of the Terms of Use, shall apply additionally. In case of conflicts, the License Terms shall prevail over the Terms of Use.
Sources
DeSpy's copy of this version is dated 2026-09-28.
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