Windows 95Operating system · Microsoft

CVE-1999-0258

MEDIUM · 5.0 CVSS v2.0 Published 1998-02-13
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
59/100
Remediation priority · Elevated
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
Bonk variation of teardrop IP fragmentation denial of service.

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

Bonk is a variant of the teardrop attack, which exploits vulnerabilities in the IP fragmentation reassembly process. The attack sends specially crafted overlapping IP fragments that cause the target system to crash or become unresponsive during fragment reassembly.

MitigationApply operating system patches for IP fragmentation handling vulnerabilities; implement network-level filtering of fragmented packets at perimeter firewalls; disable IP fragmentation if not required by the environment.

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 95Operating system
Affected:all versions
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
None
Integrity
None
Availability
Partial

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

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 operating system version
    Run 'winver' command or check System Properties to confirm the Windows version
    Affected if The system is running Windows 95 or Windows NT (any version)
  2. Check if the system is network-connected
    Verify network adapter status using 'ipconfig /all' or by checking if the network interface has an IP address
    Affected if The vulnerable Windows system has an active network connection and can receive IP traffic
  3. Confirm IP fragmentation handling is active
    Verify the system has IP protocol support enabled - check that TCP/IP is installed and bound to network adapters
    Affected if TCP/IP networking stack is enabled on the Windows 95 or NT system
  4. Review installed security patches
    Check Add/Remove Programs for Windows updates, or review the system for any post-service-pack hotfixes related to IP fragmentation (MS00-029, MS01-007, or cumulative security patches for Windows NT 4.0)
    Affected if No fragmentation-related security patches have been applied to Windows 95 or Windows NT

The environment is affected if any Windows 95 or Windows NT system with active TCP/IP networking remains unpatched and exposed to external fragmented IP traffic.

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 operating system patches for IP fragmentation handling vulnerabilities; implement network-level filtering of fragmented packets at perimeter firewalls; disable IP fragmentation if not required by the environment.

Fix this in Windows 95 Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
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Scan for this in your stack

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dbcve dependency scanner

Check whether your project pulls in CVE-1999-0258 — 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-1999-0258 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