CVE-2020-28388

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-02-09 · updated 2026-06-17
Weakness: CWE-342

Description

A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions < V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions < V2.8.20), APOGEE PXC Modular (BACnet) (All versions < V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions < V2.8.20), Nucleus NET (All versions < V5.2), Nucleus ReadyStart V3 (All versions < V2012.12), Nucleus Source Code (All versions), PLUSCONTROL 1st Gen (All versions), TALON TC Compact (BACnet) (All versions < V3.5.5), TALON TC Modular (BACnet) (All versions < V3.5.5). 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.

Affected products

Siemens Capital VSTAR: all versions
Siemens Nucleus NET: before 5.2 — fixed in 5.2
Siemens Nucleus Readystart: before 2012.12 — fixed in 2012.12
Siemens Nucleus Source Code: all versions
Siemens PLUSCONTROL 1st Gen: all versions

How to fix

Upgrade to a fixed version: Siemens Nucleus NET 5.2; Siemens Nucleus Readystart 2012.12. Check the vendor advisory for mitigations.

References

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