CVE-2023-2846
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 · uneditedAuthentication Bypass by Capture-replay vulnerability in Mitsubishi Electric Corporation MELSEC iQ-F Series main modules allows a remote unauthenticated attacker to cancel the password/keyword setting and login to the affected products by sending specially crafted packets.
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 capture-replay vulnerability in Mitsubishi Electric MELSEC iQ-F Series PLCs allows remote unauthenticated attackers to bypass authentication by capturing and replaying authentication packets, enabling them to cancel password/keyword protection and gain unauthorized login access to the affected industrial control devices.
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
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
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 FX3U PLC models on the networkScan the network for Mitsubishi FX3U series PLCs using inventory tools or by checking device banners on port 502 (Modbus/TCP) or ports 20-21 (FTP). Look for model numbers: FX3u-16MR/ES, FX3u-16MT/ES, FX3u-16MT/ESS, FX3u-32MR/ES, FX3u-32MT/ES, FX3u-32MT/ESS, FX3u-48MR/ES, FX3u-48MT/ESAffected if Any of these eight FX3U model variants are present on the network
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Verify PLC network accessibilityCheck if the identified FX3U PLCs have Ethernet ports configured and are reachable from network segments. Use ping, port scans, or check network diagrams to confirm network connectivityAffected if The affected PLC is network-connected and reachable from any IP address outside a trusted management VLAN
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Confirm password/keyword protection statusAccess the PLC via GX Works2 or GX Works3 programming software and navigate to the security settings. Check if a password, keyword, or protection lock is configured under the PLC Parameter security settingsAffected if Password or keyword protection is configured on the PLC (the vulnerability allows bypassing this protection)
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Check for external network exposureReview firewall rules, NAT configurations, and access control lists to determine if the PLC is accessible from external networks or untrusted zones. Check if port 502 (MELSEC protocol) or HTTP ports are open to the internet or DMZAffected if The PLC management or protocol ports are exposed to untrusted networks without firewall filtering
You are affected if you have any of the eight FX3U model variants (16MR/ES, 16MT/ES, 16MT/ESS, 32MR/ES, 32MT/ES, 32MT/ESS, 48MR/ES, 48MT/ES) with network accessibility and password protection enabled.
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 dataIsolate affected devices behind firewalls or network segmentation, block external access, and apply vendor patches when available. Implement additional authentication controls such as VPN access for management interfaces.
- Consultation6.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-2846 — 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-2023-2846 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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