D196g FirmwareOperating system · Mercurycom

CVE-2025-50398

CRITICAL · 9.8 CVSS v3.1 Published 2025-12-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Public exploit 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
Mercury D196G d196gv1-cn-up_2020-01-09_11.21.44 is vulnerable to Buffer Overflow in the function sub_404CAEDC via the parameter fac_password.

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 confidence

Buffer overflow vulnerability in Mercury D196G router firmware (d196gv1-cn-up_2020-01-09_11.21.44) in function sub_404CAEDC via the fac_password parameter. The critical CVSS score of 9.8 indicates potential for remote code execution without authentication.

MitigationApply vendor firmware update if available; if no patch exists, restrict network access to the device's management interface and consider replacing the device. The fac_password parameter suggests the web management interface is the attack vector.

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
D196g 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
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/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 checks

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

  1. Identify the device model
    Access the router's web interface or check the device label/marketing to confirm it is a Mercury D196G or D196g router model
    Affected if The device is a Mercury D196G/D196g router
  2. Determine the firmware version
    Log into the router's web management interface and navigate to Status or System Information page to view the firmware version, or check the file name if you have access to the firmware binary (typically contains date strings like 2020-01-09)
    Affected if The firmware version matches the affected release (d196gv1-cn-up_2020-01-09_11.21.44) or is any version of this firmware
  3. Verify the web management interface is accessible
    Attempt to access the router's IP address via HTTP/HTTPS on common ports 80 or 443 to confirm the web interface is reachable
    Affected if The web management interface responds and presents a login or configuration page
  4. Check for the fac_password parameter
    Examine the HTTP requests or HTML source of the login page for a form field named 'fac_password' - this parameter handles factory password functionality
    Affected if The fac_password parameter is present in the web interface forms

If the device is a Mercury D196G/D196g router running any version of this firmware with an accessible web management interface containing the fac_password parameter, the environment is affected by this vulnerability.

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 vendor firmware update if available; if no patch exists, restrict network access to the device's management interface and consider replacing the device. The fac_password parameter suggests the web management interface is the attack vector.

Fix this in D196g Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2025-50398 — 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 sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-50398 in production — separate from our analysis above.

No notes yet

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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