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Linux KernelOperating system · Linux

CVE-1999-0590

HIGH · 10.0 CVSS v2.0 Published 2000-06-01
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
A system does not present an appropriate legal message or warning to a user who is accessing it.

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

This CVE addresses the absence of required legal warning banners or notice messages on systems. When users connect to a system, it should display a warning banner stating the system is for authorized use only, that usage may be monitored, and that unauthorized access is prohibited. Without this banner, organizations lack documented evidence that users have been notified of acceptable use policies and monitoring practices.

MitigationDeploy appropriate legal notice and warning banners to all affected systems that display before or at the login prompt, ensuring they cover authorized use, monitoring disclosure, and consent to terms.

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
Linux KernelOperating system
Affected:= 2.6.20.1
macOSOperating system
Affected:all versions
Windows 2000Operating system
Affected:all versions
Windows 95Operating system
Affected:all versions
Windows 98Operating system
Affected:all versions
Windows NtOperating system
Affected:= 3.5.1= 4.0

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. Check for warning banner configuration on Linux systems
    Examine system login configuration files (sshd_config, PAM configuration, display manager settings) and check for Banner or legal notice directives. Look for files typically containing legal notice text in /etc or /etc/ssh/ directories, or verify if sshd Banner directive is configured.
    Affected if No legal warning banner is configured in login configuration files or no banner text is set to display before authentication.
  2. Verify presence of login warning banner on macOS
    Check if a legal banner is configured to display at the login window. This can be inspected through system preferences or by attempting a remote login (via SSH) to observe if a banner appears before authentication.
    Affected if No legal warning banner is displayed before or at the macOS login prompt.
  3. Inspect Windows system for legal notice configuration
    Check Windows registry or system policy settings for legal notice configuration. On Windows NT/2000/95/98, examine registry keys under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System for 'LegalNoticeCaption' and 'LegalNoticeText' values, or check local security policy settings.
    Affected if No legal notice caption or text is configured in Windows registry or security policies, meaning no warning banner appears at logon.
  4. Test banner display via remote access attempt
    Initiate an SSH, telnet, or remote desktop connection to the target system and observe whether a warning banner displaying authorized use, monitoring disclosure, and prohibition of unauthorized access appears before the login prompt.
    Affected if No warning banner containing authorized use and monitoring notices appears during the login sequence.

The system is affected by this CVE if no legal warning banner is configured or displayed at login, meaning users are not notified of authorized use policies and monitoring practices before authentication.

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

Deploy appropriate legal notice and warning banners to all affected systems that display before or at the login prompt, ensuring they cover authorized use, monitoring disclosure, and consent to terms.

Recommended fix High confidence
  1. This CVE describes a missing legal warning banner issue (compliance finding), not a technical security vulnerability exploitable through patching
  2. The affected operating systems (Windows 95/98/NT/2000, Linux 2.6.20.1, legacy macOS) are all end-of-life and no longer receive security updates
  3. Modern operating systems provide configuration options to display legal notices/banners at login if required by organizational policy
  4. No upgrade path is applicable as this is not a patchable vulnerability - it is a configuration/compliance requirement that applies to legacy systems no longer in use
  5. For compliance with similar requirements on current systems, configure the login banner via system settings or policy (e.g., /etc/issue on Linux, Group Policy on Windows, loginwindow preferences on macOS)

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

Fix this in Linux Kernel 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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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-1999-0590 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