dbcve.org
Capital VstarApplication · Siemens

CVE-2020-28388

MEDIUM · 5.3 CVSS v3.1 Published 2021-02-09
Fix available
A fix is available. Upgrade to 5.2 / 2012.12 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The affected Siemens products use a weak pseudo-random number generator to create TCP Initial Sequence Numbers (ISN). An attacker can predict ISN values for current and future TCP connections, enabling TCP session hijacking or connection spoofing attacks.

MitigationUpdate affected products to the specified patched versions (V3.5.5, V2.8.20, V5.2, V2012.12) and consider network segmentation to limit exposure to untrusted networks.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Capital VstarApplication
Affected:all versions
Nucleus NetApplication
Affected:< 5.2
Nucleus Source CodeApplication
Affected:all versions
Pluscontrol 1st GenApplication
Affected:all versions
Nucleus ReadystartApplication
Affected:< 2012.12

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Siemens product
    Inventory your environment for presence of Siemens Capital Vstar, Siemens Nucleus Net, Siemens Nucleus Source Code, Siemens Pluscontrol 1st Gen, or Siemens Nucleus Readystart. Check installation directories, software listings, or system documentation for these product names.
    Affected if Any of these five products are found in the environment
  2. Check Nucleus Net version
    If Siemens Nucleus Net is installed, determine its version number from the product itself, license information, or system inventory. Compare against the affected range.
    Affected if Nucleus Net version is less than 5.2 (any version below 5.2 is affected)
  3. Check Nucleus Readystart version
    If Siemens Nucleus Readystart is installed, determine its version number from the product itself, license information, or system inventory. Compare against the affected range.
    Affected if Nucleus Readystart version is earlier than 2012.12
  4. Confirm affected product type
    If the installed product is Siemens Capital Vstar, Siemens Nucleus Source Code, or Siemens Pluscontrol 1st Gen, note that all versions are vulnerable regardless of version number.
    Affected if Capital Vstar, Nucleus Source Code, or Pluscontrol 1st Gen is present in any version

The environment is affected if any of the five listed Siemens products are present, specifically Nucleus Net versions below 5.2, Nucleus Readystart versions before 2012.12, or any version of Capital Vstar, Nucleus Source Code, or Pluscontrol 1st Gen.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to 5.2 / 2012.12 or later
Fixed in 5.22012.12
Interim mitigation

Update affected products to the specified patched versions (V3.5.5, V2.8.20, V5.2, V2012.12) and consider network segmentation to limit exposure to untrusted networks.

Fix this in Capital Vstar Scoped from the published advisory
  • Consultation12.0 h
  • Implementation20.0 h
  • Testing12.0 h
  • Review / QA8.0 h
52.0 hours of engineering $9,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $14,784.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-28388 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data