dbcve.org
Mf237w FirmwareOperating system · Canon

CVE-2020-16849

HIGH · 7.5 CVSS v3.1 Published 2020-11-30
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
An issue was discovered on Canon MF237w 06.07 devices. An "Improper Handling of Length Parameter Inconsistency" issue in the IPv4/ICMPv4 component, when handling a packet sent by an unauthenticated network attacker, may expose Sensitive Information.

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 confidence

The Canon MF237w printer firmware contains an improper handling of length parameter inconsistency vulnerability in its IPv4/ICMPv4 packet processing component. An unauthenticated remote attacker can send specially crafted ICMPv4 packets to trigger the vulnerability, potentially causing the device to expose sensitive information due to incorrect length validation.

MitigationApply the latest Canon firmware update for the MF237w device. As an interim control, restrict network access to the printer by placing it behind a firewall or in a restricted VLAN, and block ICMP traffic from untrusted networks.

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
Mf237w FirmwareOperating system
Affected:= 06.07
Mf113w FirmwareOperating system
Affected:all versions
Mf212w FirmwareOperating system
Affected:all versions
Mf216n FirmwareOperating system
Affected:all versions
Mf217w FirmwareOperating system
Affected:all versions
Mf226dn FirmwareOperating system
Affected:all versions
Mf229dw FirmwareOperating system
Affected:all versions
Mf231 FirmwareOperating system
Affected:all versions

CVSS 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
None
Availability
None

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

Work through these to decide whether this CVE applies to you.

  1. Identify the Canon device model
    Access the printer's web interface (if available) or print a configuration/system page to determine the exact model number. Common ways: navigate to http://[printer-ip] in a browser, or print a page using the control panel (often via 'Menu' > 'System Settings' > 'Print Report').
    Affected if The model is one of: MF237w, MF113w, MF212w, MF216n, MF217w, MF226dn, MF229dw, or MF231.
  2. Determine the installed firmware version
    In the printer's web interface, look under 'Device Information', 'System Settings', or 'Firmware Update' section. Alternatively, print a configuration page from the control panel (Menu > System Settings > List Print > User Data List or similar) which typically lists the firmware version.
    Affected if For MF237w: firmware version equals 06.07. For MF113w, MF212w, MF216n, MF217w, MF226dn, MF229dw, or MF231: any firmware version (all versions affected).
  3. Verify IPv4 network connectivity to the printer
    From a computer on the same network, ping the printer's IPv4 address: 'ping [printer-ip]' or use 'nmap -sn [printer-ip]' to confirm the device is reachable over IPv4.
    Affected if The printer responds to ICMP echo requests (pings) or is otherwise reachable over IPv4, indicating IPv4 is enabled and accessible.
  4. Confirm ICMPv4 is reachable from untrusted networks
    Check network segmentation: determine if the printer is on the same network segment as untrusted users, or if ICMP traffic from outside the local network can reach the device. Use network scanning tools like 'nmap -sU -p123 [printer-ip]' to test ICMP accessibility, or review firewall rules allowing ICMP to the printer.
    Affected if The printer's ICMPv4 service is accessible from network segments that contain untrusted or unknown users, or ICMP is not blocked by a firewall.

The device is affected if it is a Canon MF237w (firmware 06.07) or any of the other listed models (MF113w, MF212w, MF216n, MF217w, MF226dn, MF229dw, MF231) at any firmware version, AND the device is network-accessible via IPv4 with ICMP reachable from untrusted networks.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the latest Canon firmware update for the MF237w device. As an interim control, restrict network access to the printer by placing it behind a firewall or in a restricted VLAN, and block ICMP traffic from untrusted networks.

Fix this in Mf237w Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2020-16849 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-16849 in production — separate from our analysis above.

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.

What this is

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.

What belongs here
  • 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