CVE-2019-20457
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 · uneditedAn issue was discovered on Brother MFC-J491DW C1806180757 devices. The printer's web-interface password hash can be retrieved without authentication, because the response header of any failed login attempt returns an incomplete authorization cookie. The value of the authorization cookie is the MD5 hash of the password in hexadecimal. An attacker can easily derive the true MD5 hash from this, and use offline cracking attacks to obtain administrative access to the device.
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 confidenceThe Brother MFC-J491DW printer's web interface exposes the administrator password as an MD5 hash in an incomplete authorization cookie returned with any failed login attempt. Since no authentication is required to trigger this response, an attacker can capture the hash and perform offline cracking to gain administrative access.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- 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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Confirm the printer model and check if the web interface is enabledAccess the printer's IP address via HTTP (e.g., http://<printer-ip>) in a web browser. If a Brother web interface login page loads, the web interface is enabled.Affected if The web interface is accessible and displays a Brother login page for the MFC-J491DW or related models
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Trigger a failed login attemptSubmit any incorrect username and password credentials on the login page and capture the HTTP response using browser developer tools or a proxy like Burp Suite.Affected if A response is returned without requiring authentication (no prior login session needed)
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Examine the response cookies for password hash exposureInspect the Set-Cookie headers or browser cookies in the response. Look for an 'authorization' or similar cookie that contains a 32-character hexadecimal string (indicating an MD5 hash).Affected if The cookie contains a 32-character MD5 hash value instead of a session token or empty value
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Compare your firmware version to the affected rangeCheck the printer's firmware version through the web interface (usually under 'General Setup' or 'Machine Info') or by printing a configuration page from the printer panel.Affected if The installed firmware version has not been patched by Brother for this vulnerability
Your environment is affected if the MFC-J491DW web interface is accessible and returns the administrator password as an MD5 hash in cookies when incorrect login credentials are submitted.
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 dataApply the vendor firmware update from Brother to patch this vulnerability. As a compensating control, isolate the printer on a restricted network segment and disable the web interface if not required.
- Consultation2.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
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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-2019-20457 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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