dbcve.org
Windows NtOperating system · Microsoft

CVE-1999-0581

HIGH · 10.0 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 →
100/100
Remediation priority · Urgent
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
The HKEY_CLASSES_ROOT key in a Windows NT system has inappropriate, system-critical permissions.

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 HKEY_CLASSES_ROOT registry key in Windows NT systems has overly permissive access controls, allowing unauthorized users or processes to modify critical file associations, COM object registrations, and other system configurations stored in this critical registry hive.

MitigationReview and restrict permissions on HKEY_CLASSES_ROOT to ensure only Administrators and SYSTEM have write access; remove any unnecessary or overly permissive access control entries.

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
Network
Complexity
Low
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/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. Examine HKEY_CLASSES_ROOT permissions
    Open Registry Editor (regedt32.exe) and navigate to HKEY_CLASSES_ROOT, then go to Security > Permissions or use 'regedt32.exe' and select Security > Permissions from the menu
    Affected if Any user account or group other than Administrators, SYSTEM, or Creator Owner is listed with Write or Full Control permissions
  2. Identify accounts with write access
    Review the permission entries for HKEY_CLASSES_ROOT and document which security principals (users, groups) are granted Write, Full Control, or Special Access permissions
    Affected if Non-administrative users or groups such as Users, Everyone, or Power Users have explicit Write or Full Control permissions
  3. Check for excessive inherited permissions
    In the Permissions dialog for HKEY_CLASSES_ROOT, verify if permissions are inherited from parent keys and examine the Effective Permissions for standard user accounts
    Affected if Standard users inherit Write permissions from parent containers or have Effective Permissions that include Modify or Write access
  4. Verify restricted accounts list
    Compare the permission list against expected secure baselines - only SYSTEM, Administrators, and Creator Owner should have Full Control; Users should have Read-only access
    Affected if The permission list includes any account beyond the Administrators group and SYSTEM with elevated access rights
  5. Test non-admin user access
    If available, log in as a non-administrative user and attempt to create or modify a file association key under HKEY_CLASSES_ROOT (e.g., create a new key under .txt)
    Affected if The non-administrative user can successfully create or modify registry keys in HKEY_CLASSES_ROOT

Your environment is affected if any non-administrative user or group has Write or Full Control permissions to HKEY_CLASSES_ROOT, allowing them to modify file associations, COM registrations, or other system configurations.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Review and restrict permissions on HKEY_CLASSES_ROOT to ensure only Administrators and SYSTEM have write access; remove any unnecessary or overly permissive access control entries.

Recommended fix High confidence

Upgrade to a supported Windows version (Windows 10/11 or Windows Server 2016+)

  1. No vendor patch is available for Windows NT, which has been end-of-life since 2004.
  2. Upgrade to a supported Windows operating system (such as Windows 10 or Windows 11) to receive security updates.
  3. If upgrade is not immediately possible, isolate the Windows NT system on a restricted network segment to reduce exposure.
  4. Consider replacing Windows NT systems entirely as they no longer receive security patches.
Caveat Full system migration required; legacy applications may need replacement or testing for compatibility with modern Windows

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Windows Nt Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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Scan for this in your stack

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dbcve dependency scanner

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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-1999-0581 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