CVE-1999-1132 in Windows
Summary
by MITRE
Windows NT 4.0 allows remote attackers to cause a denial of service (crash) via extra source routing data such as (1) a Routing Information Field (RIF) field with a hop count greater than 7, or (2) a list containing duplicate Token Ring IDs.
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Analysis
by VulDB Data Team • 04/20/2026
This vulnerability affects windows nt 4 0 operating systems and represents a denial of service flaw that can be exploited remotely by attackers who manipulate routing information within network packets. The vulnerability stems from insufficient validation of source routing data in the network stack implementation, specifically when processing routing information fields and token ring identifier lists. The flaw allows malicious actors to craft specially formatted packets that trigger system crashes and subsequent service disruption. According to cwe classification this represents a weakness in input validation where the system fails to properly validate routing parameters before processing them, making it susceptible to malformed data injection attacks. The vulnerability aligns with attack techniques described in the attack tree framework where adversaries can leverage network protocol implementation flaws to achieve system compromise through denial of service mechanisms.
The technical implementation of this vulnerability occurs when the windows nt 4 0 operating system receives network packets containing source routing information that violates expected parameter constraints. Specifically when the routing information field contains a hop count exceeding the maximum allowed value of seven, or when token ring identifier lists contain duplicate entries, the system fails to properly validate these inputs before attempting to process them. This leads to memory corruption or invalid pointer dereferences within the network protocol stack, ultimately causing the operating system to crash and become unresponsive. The vulnerability demonstrates a classic buffer overflow pattern where insufficient bounds checking allows malicious data to overwrite critical system memory structures, resulting in system instability and complete service interruption.
The operational impact of this vulnerability extends beyond simple system crashes as it can be exploited by remote attackers without requiring authentication or elevated privileges. This makes it particularly dangerous in networked environments where windows nt 4 0 systems may be exposed to untrusted network traffic. The vulnerability affects systems that rely on source routing mechanisms for network communication, potentially impacting critical infrastructure components that depend on legacy windows nt 4 0 implementations. Organizations with systems running this operating system face significant risk of service disruption and potential business impact when this vulnerability is exploited. The flaw also represents a broader security concern for legacy systems that may not receive regular security updates, leaving them vulnerable to exploitation by threat actors who target known weaknesses in older software implementations.
Mitigation strategies for this vulnerability should focus on immediate network segmentation and access control measures to prevent unauthorized access to systems running windows nt 4 0. Organizations should implement network filtering rules to drop packets containing source routing information or restrict the use of source routing protocols entirely. The most effective long-term solution involves migrating away from unsupported operating systems to modern platforms that receive regular security updates and have robust input validation mechanisms. System administrators should also consider disabling unnecessary network protocols and services that may be vulnerable to similar attacks. According to nist guidelines for vulnerability management, this type of flaw should be addressed through immediate patching or equivalent compensating controls, as the potential for exploitation remains high given the widespread deployment of windows nt 4 0 systems in enterprise environments. Network monitoring should be enhanced to detect anomalous routing data patterns that may indicate exploitation attempts, providing early warning capabilities for potential attacks targeting this specific vulnerability.