CVE-2008-4310 in Ruby
Summary
by MITRE
httputils.rb in WEBrick in Ruby 1.8.1 and 1.8.5, as used in Red Hat Enterprise Linux 4 and 5, allows remote attackers to cause a denial of service (CPU consumption) via a crafted HTTP request. NOTE: this issue exists because of an incomplete fix for CVE-2008-3656.
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Analysis
by VulDB Data Team • 05/25/2025
The vulnerability described in CVE-2008-4310 represents a significant denial of service weakness within the WEBrick HTTP server component of Ruby versions 1.8.1 and 1.8.5. This issue specifically targets the httputils.rb file within WEBrick's implementation, which serves as a core utility for processing HTTP requests. The vulnerability manifests when the server receives specially crafted HTTP requests that exploit a flaw in how the HTTP parser handles certain malformed input sequences. This particular weakness was identified as an incomplete remediation for CVE-2008-3656, indicating that previous attempts to address similar issues were insufficient and created a new attack surface that adversaries could exploit. The vulnerability operates at the protocol level, specifically targeting the HTTP request parsing logic that processes incoming connections to the WEBrick server.
The technical flaw stems from improper handling of malformed HTTP requests within the httputils.rb file, which causes the WEBrick server to enter an inefficient processing loop when encountering crafted input. When a remote attacker sends a specially constructed HTTP request, the server's HTTP parser becomes trapped in a CPU-intensive operation that consumes excessive processing resources. This behavior occurs because the parser fails to properly validate or terminate parsing operations when encountering malformed or unexpected HTTP header sequences. The vulnerability essentially creates a resource exhaustion condition where the server's CPU utilization spikes to 100% while attempting to process the malformed request, effectively rendering the service unavailable to legitimate users. This type of vulnerability aligns with CWE-400, which categorizes unchecked resource consumption issues, and represents a classic example of how incomplete security fixes can create new attack vectors rather than resolving existing ones.
The operational impact of CVE-2008-4310 is severe for systems running affected Ruby versions, as it enables remote attackers to perform denial of service attacks against web applications using WEBrick as their HTTP server. Organizations utilizing Red Hat Enterprise Linux 4 and 5 systems that employ Ruby applications with WEBrick components face significant risk, as a single malicious request can consume all available CPU resources and effectively crash the web service. The vulnerability is particularly dangerous because it requires no authentication or special privileges to exploit, making it an attractive target for automated attacks. Additionally, the impact extends beyond simple service disruption, as the resource exhaustion can affect other system processes and potentially lead to cascading failures in larger application environments. This vulnerability demonstrates the importance of thorough testing during security patch development and highlights the risks associated with partial fixes that address symptoms rather than root causes.
Mitigation strategies for CVE-2008-4310 should focus on immediate remediation through system updates and configuration hardening. Organizations should prioritize upgrading to patched versions of Ruby that contain complete fixes for both CVE-2008-4310 and CVE-2008-3656, ensuring that all affected systems running Ruby 1.8.1 and 1.8.5 are updated promptly. System administrators should implement network-level protections such as rate limiting and request filtering to prevent malicious requests from reaching the WEBrick server. The implementation of intrusion detection systems that can identify and block suspicious HTTP request patterns provides an additional layer of defense. Additionally, organizations should consider migrating away from WEBrick for production environments, as it was designed primarily for development purposes and lacks the robustness required for enterprise deployments. Configuration changes such as reducing timeout values and implementing connection limits can help minimize the impact of successful attacks. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network denial of service attacks, and organizations should consider implementing defensive measures against this specific attack pattern within their security operations centers.