CVE-2020-15783
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 · uneditedA vulnerability has been identified in SIMATIC S7-300 CPU family (incl. related ET200 CPUs and SIPLUS variants) (All versions), SIMATIC TDC CPU555 (All versions), SINUMERIK 840D sl (All versions). Sending multiple specially crafted packets to the affected devices could cause a Denial-of-Service on port 102. A cold restart is required to recover the service.
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 confidenceThis vulnerability in Siemens SIMATIC S7-300 CPUs, TDC CPU555, and SINUMERIK 840D sl allows remote attackers to cause a denial-of-service by sending specially crafted packets to port 102 (the S7 communication port). The attack renders the device non-functional, requiring a cold restart to recover.
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 dataall versionsall versionsall versionsall versionsall versionsall versionsall versionsall versionsCVSS 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
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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 checksWork through these to decide whether this CVE applies to you.
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Identify the installed device modelAccess the PLC engineering software (TIA Portal) or check the physical device labeling to determine the exact CPU model number (e.g., CPU 315-2 PN/DP, CPU 317-2 DP). For SINUMERIK 840D sl, check the CNC control system identification plate or system diagnostics.Affected if The device model matches any of the following: Sinumerik 840d Sl, Simatic S7-300 CPU 312, CPU 314, CPU 315-2 DP, CPU 315-2 PN, CPU 317-2 PN, CPU 317-2 DP, or CPU 315F-2 DP.
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Confirm firmware versionConnect to the CPU using SIMATIC Manager or TIA Portal and navigate to the device diagnostics or online accessible nodes to read the firmware version. For SINUMERIK 840D sl, access the system diagnostics via HMI or SINUMERIK Operate.Affected if Any firmware version is installed, as the advisory states all versions of the listed products are affected.
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Verify port 102 accessibilityUse a network scanner or port check tool (such as nmap) from an external network segment to probe port 102 (TCP 102) on the device IP address. Also check industrial network firewall rules or switch port configurations for any ACLs permitting unrestricted access.Affected if Port 102 is open and accessible from network segments outside of the trusted engineering workstation subnet, or no firewall rule blocks unauthorized IP addresses from reaching port 102.
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Review device crash logs and restart historyExamine the CPU diagnostic buffer via TIA Portal or SIMATIC Manager for entries indicating unexpected stop, cold restart required, or communication failures. For SINUMERIK, check the system alarm log for repeated 4100-series or communication-related alarms.Affected if The diagnostic buffer shows frequent unexpected stops, requires cold restarts to recover, or displays error messages indicating the S7 communication stack has failed.
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Monitor network traffic for anomalous patternsUse a network tap or industrial protocol analyzer to capture traffic on port 102 and inspect for malformed S7 communication packets, high volumes of S7 requests from single sources, or patterns inconsistent with normal engineering or HMI communications.Affected if Traffic analysis reveals specially crafted packets to port 102 that are malformed, cause protocol errors, or result in CPU fault reactions.
You are affected if your environment contains any of the listed SIMATIC S7-300 CPU models, TDC CPU555, or SINUMERIK 840D sl devices, and port 102 is accessible from untrusted network segments or the device has experienced unexplained DoS events requiring cold restart.
Generated from the published advisory. Verify against your own configuration.
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 dataApply network segmentation and firewall rules to restrict access to port 102 to only authorized IP addresses, and monitor for anomalous traffic patterns on industrial protocols.
- Consultation6.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-15783 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-15783 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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