CVE-2020-28388

mediumpriority · track · 21OT risk · elevatedstack campaign · NUMBER:JACKEPSS 0.013 · 71 %ileDEEURUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
1.35% (71st) EPSS
CVSS 5 · medium
Is it mine?
48 products
Check your exposure
Who says so?
6 sources
cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

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.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

02

cvss

Technical severity, 0–10. One row per scoring source.

6.5
010

base score 0–10 · higher = more severe · hover a vector to decode

v2.05mediumAV:N/AC:L/Au:N/C:N/I:P/A:Nprimary · NVD / NIST USexploitability 10 · impact 2.9
v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:Nprimary · NVD / NIST USexploitability 3.9 · impact 1.4
v3.06.5mediumCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:Lsecondary · CISA US
v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L/E:P/RL:O/RC:Csecondary · CISA US
v3.15.3mediumAV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:Nsecondary · FSTEC (BDU) RU
v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L/E:P/RL:O/RC:Csecondary · ENISA EU
v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:Lsecondary · productcert@siemens.com DEexploitability 3.9 · impact 2.5
v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L/E:P/RL:O/RC:Csecondary · Siemens ProductCERT DE
v3.14.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)
03

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS
04

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-330USCWE-342USCWE-342USCWE-342USCWE-342US
05

affected products (48)

Products and version ranges known to be affected.

showing 20 of 48
06

advisories (7)

Vendor and ecosystem advisories describing this.

  • SSA-180579SSA-180579: Privilege Management Vulnerability and Multiple Nucleus RTOS Vulnerabilities in APOGEE/TALON Field Panels before V3.5.5/V2.8.202022-12-13csaf · siemens_psirtDE

    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.

  • SSA-362164SSA-362164: Predictable Initial Sequence Numbers in the TCP/IP Stack of Nucleus RTOS2021-02-09csaf · siemens_psirtDE

    The networking component (Nucleus NET) in Nucleus Real-Time Operating System (RTOS) use Initial Sequence Numbers for TCP-Sessions that are predictable. 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.

  • SSA-436469SSA-436469: TCP Vulnerability in APOGEE/TALON Field Panels2022-12-13csaf · siemens_psirtDE

    A TCP sequence vulnerability in the APOGEE PXC and TALON TC series of products could allow an attacker to execute a denial of service attack by sending specially crafted packets to the device. Siemens has released updates for the affected products and recommends to update to the latest versions.

  • WID-SEC-W-2023-1987TCP/IP Stack: Mehrere SchwachstellenDeutsch2021-02-11csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in TCP/IP Stack ausnutzen, um beliebigen Programmcode auszuführen, einen Denial-of-Service-Zustand herbeiführen oder Sicherheitsvorkehrungen umgehen.

  • ICSA-21-042-01Multiple Embedded TCP/IP Stacks (Update B)2021-02-11icsa · cisa_csaf_otUS

    Successful exploitation of weak initial sequence numbers (ISN) can be used to hijack or spoof TCP connections, cause denial-of-service conditions, inject malicious data, or bypass authentication.

  • ICSA-21-068-08Siemens Energy PLUSCONTROL 1st Gen2021-03-09icsa · cisa_csaf_otUS

    Operators of critical power systems (e.g.'TSOs or DSOs) worldwide are usually required by regulations to build resilience into the power grids by applying multi-level redundant secondary protection schemes. It is therefore recommended that the operators check whether appropriate resilient protection measures are in place. The risk of cyber incidents impacting the grid's reliability can thus be minimized by virtue of the grid design. Siemens strongly recommends applying the provided security updates using the corresponding tooling and documented procedures made available with the product. If supported by the product, an automated means to apply the security updates across multiple product instances may be used. Siemens strongly recommends prior validation of any security update before being applied, and supervision by trained staff of the update process in the target environment. As a general security measure Siemens strongly recommends to protect network access with appropriate mechanisms (e.g.'firewalls, segmentation, VPN). It is advised to configure the environment according to our operational guidelines in order to run the devices in a protected IT environment.

  • ICSA-22-349-16Siemens APOGEE and TALON2022-12-13icsa · cisa_csaf_otUS

    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.

07

also known as (8)

Other names and identifiers for this entity.

08

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducert_bundcisa_csaf_otsiemens_psirtNVDCVE.orgMITRE
published 2021-02-09modified 2026-06-17
09

references (16)

External citations — patches, advisories, analysis.

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