CVE-2020-28220
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 CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability exists in Modicon M258 Firmware (All versions prior to V5.0.4.11) and SoMachine/SoMachine Motion software (All versions), that could cause a buffer overflow when the length of a file transferred to the webserver is not verified.
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 confidenceA buffer overflow vulnerability (CWE-119) exists in the webserver component of Modicon M258 Firmware (versions prior to V5.0.4.11) and SoMachine/SoMachine Motion software (all versions). The vulnerability is triggered when a file is transferred to the webserver without proper length validation, allowing an attacker to overwrite adjacent memory and potentially execute arbitrary code or cause denial of service.
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< 5.0.4.11all 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
- Adjacent
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/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 Schneider Electric productDetermine if the system runs Modicon M258 controller, SoMachine, or SoMachine Motion software. Check product documentation, installed programs, or controller identity.Affected if The product is Modicon M258, SoMachine, or SoMachine Motion
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Check Modicon M258 firmware versionAccess the controller through EcoStruxure Machine Expert, Unity Pro, or the controller's web interface to retrieve the firmware version. Compare the version number to 5.0.4.11.Affected if Modicon M258 firmware version is below 5.0.4.11
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Verify if the webserver component is enabledCheck the controller or software configuration to determine if the webserver feature is active. This may be in the controller settings, web server configuration, or network services list.Affected if The webserver component is enabled and accessible on the network
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Check network exposure of the webserverReview firewall rules, network segmentation, and access controls to determine if the webserver HTTP port (typically port 80/443) is exposed to untrusted networks or the internet.Affected if The webserver is reachable from untrusted network segments or directly from the internet
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Confirm file transfer capability is accessibleDetermine if the webserver file transfer/upload functionality is accessible to users or attackers. This may be tested by attempting to access the webserver upload endpoint or reviewing service configuration.Affected if File transfer/upload functionality on the webserver is accessible without additional authentication barriers beyond default settings
A system is affected if it runs Modicon M258 firmware below V5.0.4.11 (or any version of SoMachine/SoMachine Motion) AND has the webserver component enabled and network-accessible.
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 data5.0.4.11
Update Modicon M258 firmware to V5.0.4.11 or later. For SoMachine/SoMachine Motion, apply compensating controls such as network segmentation, firewall rules restricting webserver access, and input validation at network boundaries until a fix is available from Schneider Electric.
- Consultation8.0 h
- Implementation12.0 h
- Testing8.0 h
- Review / QA4.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2020-28220 — 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-2020-28220 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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- 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
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