CVE-1999-0258 in Windows
Prediction
by VulDB Data Team • 04/17/2026
A vulnerability has been found in Microsoft Windows 95/NT 4.0. The affected element is an unknown function of the component IP Fragmentation Handler. The manipulation leads to denial of service (Bonk). Remote exploitation of the attack is possible. The exploit has been disclosed to the public and may be used. Upgrading to version 98 and 2000 is sufficient to fix this issue. Upgrading the affected component is recommended.
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Analysis
by VulDB Data Team • 04/17/2026
The vulnerability described in CVE-1999-0258 represents a sophisticated denial of service attack targeting IP fragmentation handling mechanisms within network protocols. This specific variant of the teardrop attack exploits weaknesses in how operating systems process fragmented internet protocol packets, particularly affecting systems that implement the bonk attack vector. The vulnerability operates by sending malformed IP fragments designed to confuse the receiving system's reassembly process, ultimately leading to system crashes or resource exhaustion that renders network services unavailable to legitimate users.
The technical flaw underlying this vulnerability stems from inadequate validation of IP fragment offset fields and fragment size parameters during the packet reassembly phase. When a system receives overlapping or improperly ordered IP fragments, the reassembly logic fails to properly handle these edge cases, causing memory corruption or infinite loop conditions. This type of vulnerability aligns with CWE-129, which addresses improper validation of input ranges, and CWE-128, concerning output buffer underruns. The attack specifically targets the network stack implementation where IP fragments are processed, exploiting assumptions about fragment ordering and size that do not hold true for maliciously crafted packets.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire network infrastructure. Systems affected by this vulnerability may experience complete denial of service for network communications, requiring manual intervention to restore normal operation. The attack can be executed with minimal resources and does not require authentication, making it particularly dangerous for network administrators who must maintain continuous availability of services. Organizations running affected systems face significant operational risks including data loss, extended downtime, and potential financial losses due to service interruption. The vulnerability affects multiple operating systems including various versions of unix and windows platforms, making it a widespread concern for network security teams.
Mitigation strategies for CVE-1999-0258 require immediate implementation of network filtering rules to block malformed IP fragments at network boundaries. System administrators should implement ingress and egress filtering to prevent fragmented packets with overlapping offsets from reaching vulnerable systems. Network security appliances and firewalls should be configured to drop IP fragments with suspicious parameters or to enforce proper fragment reassembly limits. The implementation of intrusion detection systems with signature-based detection capabilities can help identify and block attack traffic before it reaches vulnerable hosts. Additionally, system updates and patches should be applied immediately to address the underlying implementation flaws in IP fragment handling. Organizations should also implement monitoring procedures to detect unusual network traffic patterns that may indicate attempted exploitation of this vulnerability. The attack pattern aligns with techniques described in the attack tree framework under the MITRE ATT&CK methodology, specifically targeting the network service availability pillar through the use of malformed packet delivery mechanisms.