CVE-2014-8080 in Ruby
Summary
by MITRE
The REXML parser in Ruby 1.9.x before 1.9.3-p550, 2.0.x before 2.0.0-p594, and 2.1.x before 2.1.4 allows remote attackers to cause a denial of service (memory consumption) via a crafted XML document, aka an XML Entity Expansion (XEE) attack.
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Analysis
by VulDB Data Team • 05/10/2026
The vulnerability identified as CVE-2014-8080 represents a critical denial of service weakness in Ruby's REXML parser that affects multiple versions of the Ruby programming language. This issue stems from inadequate handling of XML entity expansion within the parser implementation, creating a scenario where maliciously crafted XML documents can trigger excessive memory consumption. The vulnerability specifically impacts Ruby versions 1.9.x before 1.9.3-p550, 2.0.x before 2.0.0-p594, and 2.1.x before 2.1.4, making it a widespread concern across the Ruby ecosystem during that period. The flaw allows remote attackers to exploit the parser's failure to properly limit entity expansion, enabling them to construct XML documents that cause the application to consume excessive system resources.
The technical root cause of this vulnerability lies in the XML parser's inability to effectively manage entity references within XML documents. When the REXML parser encounters XML entities, it recursively expands them without sufficient safeguards against excessive nesting or expansion patterns. This behavior creates a condition where an attacker can craft XML documents containing deeply nested entity references or circular entity definitions that cause the parser to consume memory at an exponential rate. The vulnerability operates under the common weakness enumeration CWE-400, which categorizes it as an Uncontrolled Resource Consumption vulnerability, specifically manifesting as a denial of service through excessive memory allocation. The parser's processing logic fails to implement proper limits on entity expansion depth or total expansion size, allowing malicious input to trigger resource exhaustion.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire application availability. When exploited, the vulnerability can cause applications parsing untrusted XML input to consume all available memory resources, leading to process termination or system instability. This makes it particularly dangerous in web applications, API services, or any system that processes external XML data from untrusted sources. The attack vector is remote and requires no authentication, making it easily exploitable by malicious actors on public networks. Applications using Ruby's REXML parser for processing XML from external sources such as web services, configuration files, or user uploads become vulnerable to this attack. The vulnerability can be classified under the attack technique ATT&CK T1499.004 which describes "Resource Hijacking" through excessive memory consumption, demonstrating how this weakness can be leveraged to exhaust system resources and deny legitimate service access.
Mitigation strategies for CVE-2014-8080 focus on both immediate patching and defensive programming practices. The primary solution involves updating Ruby installations to versions that include the security fixes, specifically Ruby 1.9.3-p550, 2.0.0-p594, and 2.1.4 or later. Organizations should prioritize patching affected systems and verifying that all Ruby applications are running on secure versions. Additionally, defensive measures include implementing XML parser configuration limits to prevent excessive entity expansion, such as setting maximum entity expansion depths and total expansion sizes. Developers should also consider implementing input validation and sanitization for all XML processing, particularly when handling external data sources. The implementation of proper XML schema validation and the use of more secure XML parsers that implement built-in protection mechanisms can further reduce the risk. Organizations should also establish monitoring for unusual memory consumption patterns that might indicate exploitation attempts, and maintain up-to-date security assessments of their Ruby applications to identify similar vulnerabilities in other components of their software stack.