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CVE-2020-28388

19
FAUCET Score

CVE-2020-28388 describes a vulnerability in Siemens APOGEE/TALON field panels and Nucleus RTOS products where TCP Initial Sequence Numbers (ISNs) are generated using an insufficiently random source. This predictability allows an attacker to potentially hijack existing TCP sessions or spoof future connections. Rated as Medium severity (CVSS 5.3), the vulnerability requires no user interaction or privileges, but its impact is limited to integrity. There is no known active exploitation, public exploit code, or KEV listing, though it has garnered some community discussion and media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:a:siemens:capital_vstar:*:*:*:*:*:*:*:*
< 5.2CPE matchmatch criteria
cpe:2.3:a:siemens:nucleus_net:*:*:*:*:*:*:*:*
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:a:siemens:nucleus_source_code:*:*:*:*:*:*:*:*
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:a:siemens:pluscontrol_1st_gen:*:*:*:*:*:*:*:*
< 2012.12CPE matchmatch criteria
cpe:2.3:a:siemens:nucleus_readystart:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
LOW
Exploitability Score
3.9
Impact Score
2.5
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.55%
Probability of exploitation in next 30 days
EPSS Percentile
72.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0155 is in the 56th percentile among its peer group of 23,701 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

cert-portal.siemens.com / productcert/pdf/ssa-180579.pdf
cert-portal.siemens.com / productcert/pdf/ssa-344238.pdf
Vendor Advisory
cert-portal.siemens.com / productcert/pdf/ssa-362164.pdf
Vendor Advisory
cert-portal.siemens.com / productcert/pdf/ssa-436469.pdf