Skip to content
Noroxi
NVD / CVE Program· CNA siemens

CVE-2020-28388: A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions < V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions <

Noroxi assessment

Priority: Monitor (action score 21/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.3% (FIRST EPSS); higher than 71.5% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • According to the record, no fixed version is available yet.

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.3 · v3.1—No exploit No fix recorded
Published
Feb 9, 2021
Updated
Jun 16, 2026
EPSS
1.3% · 71th percentile

Report tools

JSON

Action score

21

Monitor

Low priority for now.

CVSS
21 / 40 · 5.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.3%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.3
CNA · siemens
6.5
1.2 point gap

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L/E:P/RL:O/RC:C

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2020-28388

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for siemens records

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
siemenscapital vstar
siemensnucleus net
siemensnucleus source code
siemenspluscontrol 1st gen
siemensnucleus readystart
armarm
mipsmips
powerpc projectpowerpc

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • siemens capital vstarall versions
  • siemens nucleus netbefore 5.2
  • siemens nucleus readystartbefore 2012.12
  • siemens nucleus source codeall versions
  • siemens pluscontrol 1st genall versions

Versions reported by the vendor

Affected version ranges reported by the assigning authority (siemens). Independent of NVD's CPE analysis and usually ahead of it.

  • Siemens APOGEE PXC Compact (BACnet)

    • All versions < V3.5.5affected

  • Siemens APOGEE PXC Compact (P2 Ethernet)

    • All versions < V2.8.20affected

  • Siemens APOGEE PXC Modular (BACnet)

    • All versions < V3.5.5affected

  • Siemens APOGEE PXC Modular (P2 Ethernet)

    • All versions < V2.8.20affected

  • Siemens Nucleus NET

    • All versions < V5.2affected

  • Siemens Nucleus ReadyStart V3

    • All versions < V2012.12affected

  • Siemens Nucleus Source Code

    • All versionsaffected

  • Siemens PLUSCONTROL 1st Gen

    • All versionsaffected

  • Siemens TALON TC Compact (BACnet)

    • All versions < V3.5.5affected

  • Siemens TALON TC Modular (BACnet)

    • All versions < V3.5.5affected

Same product

siemens: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-31884A vulnerability has been identified in APOGEE MBC (PPC) (BACnet) (All versions), APOGEE MBC (PPC) (P2 Ethernet) (All versions), APOGEE MEC (
    39Monitor
  • CVE-2021-31890A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic R20-11 (All versions
    37Monitor
  • CVE-2021-31889A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic R20-11 (All versions
    37Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2019-13939Jan 16, 2020 · A vulnerability has been identified in APOGEE MEC/MBC/PXC (P2) (All versions < V2.8.2), APOGEE PXC Compact (BACnet) (All versions < V3.5.3),
    28Monitor
  • Later →CVE-2021-25663Apr 22, 2021 · A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic R20-11 (All versions
    35Monitor
  • Later →CVE-2021-25664Apr 22, 2021 · A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic R20-11 (All versions
    35Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
low · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-342 · Predictable Exact Value from Previous Values

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records