ICSA-21-068-06: Siemens TCP/IP Stack Vulnerabilities-AMNESIA:33 in SENTRON PAC / 3VA Devices (Update C)

CISA's summary

Summary: Security researchers discovered and disclosed 33 vulnerabilities in several open-source TCP/IP stacks for embedded devices, also known as "AMNESIA:33" vulnerabilities. This advisory describes the impact of two of these vulnerabilities (CVE-2020-13987, CVE-2020-17437) to Siemens products. Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where updates are not available. The impact of another "AMNESIA:33" vulnerability (CVE-2020-13988) is described in Siemens Security Advisory SSA-541017.

Products, as the advisory lists them

DeSpy has not checked any unit, hardware revision or firmware.

Vulnerabilities in this advisory

• CVE-2020-13987 — CVE-2020-13987 · CWE-125

  The TCP/IP stack (uIP) in affected devices is vulnerable to out-of-bounds read when calculating the checksum for IP packets. (FSCT-2020-0009) An attacker located in the same network could trigger a Denial-of-Service condition on the device by sending a specially crafted IP packet.

• CVE-2020-17437 — CVE-2020-17437 · CWE-787

  The TCP/IP stack (uIP) in affected devices is vulnerable to out-of-bounds write when processing TCP packets with urgent pointer (URG) where the location of the TCP data payload is calculated improperly. (FSCT-2020-0018) An attacker located in the same network could trigger a Denial-of-Service condition on the device by sending a specially crafted IP packet.

Acknowledgments, as the advisory lists them

• Siemens ProductCERT: reporting this vulnerability to CISA.
• Cybersecurity and Infrastructure Security Agency (CISA): coordination efforts
• CERT Coordination Center (CERT/CC): coordination efforts
• Daniel dos Santos, Jos Wetzels, Amine Amri, Forescout Technologies: coordinated disclosure

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

• The advisory at cisa.gov
• The CSAF document (JSON)

DeSpy's copy of this version is dated 2026-09-28.