ICSA-22-349-16: Siemens APOGEE and TALON

CISA's summary

Summary: APOGEE PXC / TALON TC field panels (BACnet before V3.5.5 and P2 Ethernet before V2.8.20) contain multiple vulnerabilities: - CVE-2022-45937: A privilege management vulnerability that could allow low privilege authenticated attackers to gain high privilege access. - CVE-2020-28388: Predictable Initial Sequence Numbers in the TCP/IP Stack of Nucleus RTOS (real-time operating system) used by the affected products. - Several vulnerabilities in the DNS (domain name service) implementation of Nucleus RTOS. Siemens has released updates for the affected products and recommends to update to the latest versions.

Products, as the advisory lists them

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

Vulnerabilities in this advisory

• CVE-2020-15795 — CVE-2020-15795 · CWE-787

  The DNS domain name label parsing functionality does not properly validate the names in DNS-responses. The parsing of malformed responses could result in a write past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to execute code in the context of the current process or cause a denial-of-service condition.

• CVE-2020-27009 — CVE-2020-27009 · CWE-823

  The DNS domain name record decompression functionality does not properly validate the pointer offset values. The parsing of malformed responses could result in a write past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to execute code in the context of the current process or cause a denial-of-service condition.

• CVE-2020-27736 — CVE-2020-27736 · CWE-170

  The DNS domain name label parsing functionality does not properly validate the null-terminated name in DNS-responses. The parsing of malformed responses could result in a read past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to cause a denial-of-service condition or leak the read memory.

• CVE-2020-27737 — CVE-2020-27737 · CWE-125

  The DNS response parsing functionality does not properly validate various length and counts of the records. The parsing of malformed responses could result in a read past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to cause a denial-of-service condition or leak the memory past the allocated structure.

• CVE-2020-27738 — CVE-2020-27738 · CWE-788

  The DNS domain name record decompression functionality does not properly validate the pointer offset values. The parsing of malformed responses could result in a read access past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to cause a denial-of-service condition.

• CVE-2020-28388 — CVE-2020-28388 · CWE-342

  Initial Sequence Numbers (ISNs) for TCP connections are derived from an insufficiently random source. As a result, the ISN of current and future TCP connections could be predictable. An attacker could hijack existing sessions or spoof future ones.

• CVE-2021-25677 — CVE-2021-25677 · CWE-330

  The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.

• CVE-2022-45937 — CVE-2022-45937 · CWE-284

  A low privilege authenticated attacker with network access to the integrated web server could download sensitive information from the device containing user account credentials.

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

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

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