CVE-2003-1510 in TinyWeb
Summary
by MITRE
TinyWeb 1.9 allows remote attackers to cause a denial of service (CPU consumption) via a ".%00." in an HTTP GET request to the cgi-bin directory.
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Analysis
by VulDB Data Team • 07/13/2025
The vulnerability described in CVE-2003-1510 affects TinyWeb version 1.9, a lightweight web server implementation that was widely used in embedded systems and small-scale deployments during the early 2000s. This particular flaw represents a classic example of a resource exhaustion attack that exploits improper input validation mechanisms within the web server's handling of file paths and URL decoding processes. The vulnerability specifically targets the cgi-bin directory, which serves as a conventional location for executable scripts and programs in web server environments, making it a critical attack surface for malicious actors seeking to disrupt service availability.
The technical mechanism behind this vulnerability involves the manipulation of HTTP GET requests through the inclusion of null byte sequences encoded as ".%00." within the requested file path. When TinyWeb processes such requests, it fails to properly sanitize or validate the presence of null bytes in the URL path, causing the server to enter an infinite loop or consume excessive CPU resources during the file resolution process. This occurs because the web server's internal path parsing logic does not adequately handle null byte sequences, leading to malformed path traversal attempts that cause the processor to continuously iterate through invalid memory locations or file system operations. The vulnerability operates at the application layer of the network stack, specifically within the HTTP request processing module where URL decoding and file path resolution occur, making it particularly effective for causing system resource exhaustion without requiring authentication or sophisticated attack vectors.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by remote attackers to perform sustained denial of service attacks against systems running TinyWeb 1.9. The CPU consumption issue can escalate to complete system unresponsiveness, particularly on resource-constrained embedded devices where the web server may be the primary or only service running. This vulnerability is particularly dangerous in environments where availability is critical, such as industrial control systems, network infrastructure devices, or IoT deployments where a single attack can render entire systems inoperable. The attack requires minimal technical expertise to execute, as it only involves crafting a specific URL pattern that can be automated through simple scripts or web-based tools, making it a preferred method for attackers seeking to disrupt services without requiring advanced penetration testing capabilities.
Mitigation strategies for this vulnerability should focus on both immediate patching and architectural improvements to prevent similar issues in the future. The most effective immediate solution involves upgrading to a patched version of TinyWeb that properly validates and sanitizes URL paths, particularly those containing null byte sequences or other special characters. System administrators should also implement network-level protections such as firewall rules that restrict access to the cgi-bin directory or apply URL filtering mechanisms that can detect and block requests containing suspicious null byte patterns. From a defensive perspective, this vulnerability aligns with CWE-129, which addresses improper validation of input boundaries, and demonstrates characteristics consistent with ATT&CK technique T1499.004 for network denial of service attacks. Organizations should also consider implementing monitoring solutions that can detect unusual CPU consumption patterns or sustained high load conditions that may indicate exploitation attempts. The vulnerability serves as a reminder of the importance of proper input validation and the critical need for thorough security testing of web server implementations, particularly in embedded environments where patch management may be challenging or impossible.