CVE-2020-7502
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-787: Out-of-bounds Write vulnerability exists in Modicon M218 Logic Controller (Firmware version 4.3 and prior), which may cause a Denial of Service when specific TCP/IP crafted packets are sent to the Modicon M218 Logic Controller.
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 · moderate confidenceCWE-787 out-of-bounds write vulnerability in Modicon M218 Logic Controller firmware version 4.3 and prior allows remote attackers to cause a Denial of Service by sending specifically crafted TCP/IP packets to the target device.
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<= 4.3CVSS 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.
-
Confirm device is a Modicon M218 controllerAccess the controller via Schneider Electric's EcoStruxure Machine Expert or check the physical device labeling to verify the model number is Modicon M218Affected if The device is not a Modicon M218 controller (different models are not affected by this CVE)
-
Check the installed firmware versionConnect to the controller via EcoStruxure Machine Expert or access the web server on the controller to view the firmware version informationAffected if Firmware version is 4.3 or earlier (versions 4.3 and prior are affected)
-
Verify TCP/IP communication is enabledCheck the controller's network configuration settings in EcoStruxure Machine Expert under the TCP/IP stack configuration to confirm Ethernet communication is activeAffected if TCP/IP stack is enabled and configured - the vulnerability is triggered via specifically crafted TCP/IP packets
-
Assess network exposure of the controllerReview network firewall rules and segment the controller is placed on to determine if untrusted network traffic can reach port 502 (Modbus/TCP) or other TCP services on the controllerAffected if The controller is accessible from untrusted networks without firewall filtering - this allows remote attackers to send the malicious packets
A user is affected if they have a Modicon M218 controller running firmware version 4.3 or earlier with TCP/IP enabled and exposed to untrusted network traffic.
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 dataUpdate Modicon M218 firmware to a version newer than 4.3; implement network segmentation and firewall rules to restrict untrusted TCP/IP traffic to the controller as a compensating control.
- Consultation3.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,072.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-7502 — 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-2020-7502 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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