CVE-2014-3243 in SOAPpy
Summary
by MITRE
SOAPpy 0.12.5 does not properly detect recursion during entity expansion, which allows remote attackers to cause a denial of service (memory and CPU consumption) via a crafted SOAP request containing a large number of nested entity references.
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Analysis
by VulDB Data Team • 03/04/2025
The vulnerability identified as CVE-2014-3243 affects SOAPpy version 0.12.5 and represents a critical denial of service weakness that stems from inadequate recursion detection during XML entity expansion processes. This flaw exists within the SOAPpy library, which is a python-based implementation of the Simple Object Access Protocol that facilitates web service communication. The vulnerability manifests when the library fails to properly monitor or limit nested entity references within SOAP requests, creating a scenario where malicious actors can exploit this weakness to consume excessive system resources. The issue falls under the category of XML External Entity (XXE) processing vulnerabilities, specifically related to entity expansion recursion that can lead to resource exhaustion attacks.
The technical implementation of this vulnerability occurs during the parsing of SOAP messages that contain crafted XML entities with deep nesting structures. When SOAPpy processes such requests, it recursively expands entity references without sufficient bounds checking or depth limitations, allowing attackers to construct malicious payloads that create exponentially growing entity expansions. This recursive expansion causes the parser to consume increasing amounts of memory and CPU cycles as it processes each level of nesting, eventually leading to system resource exhaustion. The flaw operates at the XML parsing layer where entity references are resolved, and the lack of proper recursion depth limits enables attackers to construct requests that can cause the application to consume all available system resources. This behavior aligns with CWE-400, which categorizes the vulnerability as an unchecked resource consumption issue, and can be classified under the ATT&CK technique T1499.1 for resource exhaustion attacks.
The operational impact of this vulnerability is severe as it allows remote attackers to perform denial of service attacks against systems that utilize SOAPpy for processing SOAP requests. An attacker can construct a single malicious SOAP request containing thousands or millions of nested entity references that will cause the target system to consume excessive memory and CPU resources, potentially leading to complete system unresponsiveness or application crashes. The attack requires minimal privileges since it operates at the network level and can be executed against any system processing SOAP requests through the vulnerable SOAPpy library. The resource consumption pattern is particularly damaging because it grows exponentially with each level of nesting, meaning that even relatively small payloads can cause significant system impact. This vulnerability affects web services, enterprise applications, and any system that relies on SOAPpy for SOAP message processing, making it a widespread concern for organizations maintaining legacy systems.
Mitigation strategies for CVE-2014-3243 primarily focus on updating to patched versions of SOAPpy or implementing proper input validation and resource limits. Organizations should immediately upgrade to SOAPpy versions that include recursion detection and entity expansion limits to prevent the exploitation of this vulnerability. Additionally, implementing XML parsing restrictions such as setting maximum entity expansion limits, disabling external entity resolution, and configuring proper input validation can help reduce the attack surface. Network-level protections including rate limiting, request size restrictions, and intrusion detection systems can also provide defense-in-depth measures. The implementation of proper XML parsing configurations that limit the depth of entity expansion and prevent recursive entity references represents the most effective technical countermeasure. Organizations should also consider migrating away from vulnerable libraries to more modern and secure alternatives that properly handle XML entity processing and include built-in protections against resource exhaustion attacks. This vulnerability highlights the importance of proper XML parsing security practices and demonstrates how seemingly simple parsing issues can lead to significant denial of service consequences.