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Windows NtOperating system · Microsoft

CVE-1999-0549

HIGH · 7.2 CVSS v2.0 Published 1999-01-01
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
77/100
Remediation priority · High
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
Windows NT automatically logs in an administrator upon rebooting.

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

Windows NT systems can be configured to automatically log in an administrator account upon reboot by setting the AutoAdminLogon registry value and storing plaintext credentials in the registry. This bypasses normal authentication mechanisms and grants immediate administrative access to anyone who can access the system after a reboot.

MitigationDisable the AutoAdminLogon feature by removing the corresponding registry keys and ensure systems require manual authentication at boot. Never store plaintext credentials in configuration files or the registry.

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
Windows NtOperating 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
Local
Complexity
Low
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:L/AC:L/Au:N/C:C/I:C/A:C

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. Check if AutoAdminLogon is enabled
    Examine the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon and look for the value named AutoAdminLogon. If present, note its data value.
    Affected if The value is set to 1 (enabled)
  2. Check for stored plaintext password
    Examine the same registry path HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon and look for a value named DefaultPassword.
    Affected if The DefaultPassword value exists and contains any data (plaintext password is stored)
  3. Identify the configured auto-logon account
    Examine the registry value DefaultUserName in the same Winlogon key to determine which account is configured for automatic logon.
    Affected if DefaultUserName points to an administrative or privileged account

A system is affected if AutoAdminLogon is set to 1 and DefaultPassword contains a plaintext password in the Winlogon registry key, allowing bypass of authentication after reboot.

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

Disable the AutoAdminLogon feature by removing the corresponding registry keys and ensure systems require manual authentication at boot. Never store plaintext credentials in configuration files or the registry.

Fix this in Windows Nt Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
4.0 hours of engineering $750
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Scan for this in your stack

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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 sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-1999-0549 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