CVE-2001-0460 in Websweeper
Summary
by MITRE
Websweeper 4.0 does not limit the length of certain HTTP headers, which allows remote attackers to cause a denial of service (memory exhaustion) via an extremely large HTTP Referrer: header.
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Analysis
by VulDB Data Team • 10/06/2025
The vulnerability identified as CVE-2001-0460 affects Websweeper 4.0, a web application firewall and security scanning tool designed to protect web servers from various cyber threats. This particular flaw represents a classic denial of service vulnerability that exploits the application's insufficient input validation mechanisms for HTTP headers. The vulnerability specifically targets the Referrer header processing functionality within the software's HTTP request handling code, where the application fails to implement proper length limitations on incoming header values.
The technical implementation of this vulnerability stems from the absence of input sanitization and boundary checking within the Websweeper 4.0 codebase. When the application receives an HTTP request containing a Referrer header, it processes the entire header value without imposing any reasonable limits on its size. This design flaw allows malicious actors to craft specially crafted HTTP requests with extraordinarily long Referrer headers, potentially reaching several kilobytes or even megabytes in size. The application's memory management system allocates resources based on the reported header length without proper validation, leading to exponential memory consumption as the software attempts to process these oversized headers.
From an operational perspective, this vulnerability presents a significant risk to web server availability and system stability. Remote attackers can exploit this weakness to consume excessive memory resources on the target system, potentially leading to complete system crashes or service unavailability. The memory exhaustion effect occurs because the application's buffer allocation mechanisms do not account for maliciously oversized input, causing the system to allocate increasingly larger memory blocks until system resources are depleted. This type of denial of service attack can be particularly damaging in environments where the web application firewall is critical to security operations, as it could prevent legitimate security scanning and monitoring functions from operating properly.
The vulnerability aligns with CWE-122, which describes improper restriction of operations within a limited memory buffer, and represents a variant of the broader class of buffer overflow and memory exhaustion attacks. From an adversarial perspective, this weakness maps to ATT&CK technique T1499.004, which covers network denial of service attacks through resource exhaustion. The attack vector requires minimal technical sophistication, as attackers only need to construct HTTP requests with oversized headers, making this vulnerability particularly dangerous as it can be exploited by adversaries with basic networking knowledge. Organizations utilizing Websweeper 4.0 should implement immediate mitigations including header size limitations, input validation mechanisms, and monitoring for anomalous header lengths to prevent exploitation of this vulnerability.
The root cause of this issue demonstrates a fundamental security flaw in the software's defensive programming practices, where proper input validation and resource management were not adequately implemented. This vulnerability highlights the critical importance of defensive coding techniques and the necessity of implementing proper bounds checking on all user-supplied input data, particularly in security-critical applications where resource exhaustion attacks can have severe operational consequences. The lack of rate limiting and header size enforcement mechanisms in the application's architecture creates an exploitable gap that directly impacts system availability and reliability.