CVE-2026-92987 in roxmltree
Summary
by MITRE • 09/17/2026
roxmltree through 0.21.1 performs quadratic-time attribute and namespace validation during XML parsing without limits on attribute count. Attackers can craft XML documents with tens of thousands of attributes on a single element to consume excessive CPU time and cause denial of service.
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Analysis
by VulDB Data Team • 09/17/2026
The vulnerability identified in the roxmltree library, affecting versions through 0.21.1, represents a significant security risk rooted in algorithmic complexity flaws during XML parsing operations. This issue is classified under CWE-400, which denotes uncontrolled resource consumption due to quadratic-time behavior in attribute and namespace validation processes. The core technical flaw lies in the library's handling of XML elements that contain an excessive number of attributes or namespaces. Instead of employing efficient data structures such as hash maps for constant-time lookups, the implementation utilizes linear search mechanisms within loops that scale quadratically relative to the input size. This design choice means that as the number of attributes increases, the processing time does not grow linearly but rather squares, leading to exponential degradation in performance.
Attackers can exploit this vulnerability by crafting malicious XML documents containing tens of thousands of attributes on a single element. When such a document is processed by an application relying on roxmltree, the parser enters a prolonged state of high CPU utilization as it attempts to validate each attribute against existing ones and namespaces. This behavior effectively creates a denial-of-service condition where legitimate services are starved of computational resources. The impact extends beyond simple performance degradation; in web applications or API gateways that parse XML input from untrusted sources, this can lead to complete service unavailability, causing significant operational disruption and potential financial loss due to downtime.
From an offensive security perspective, this vulnerability aligns with the ATT&CK technique T1496, Resource Hijacking, specifically within the context of computational exhaustion. The attack vector typically involves sending a specially crafted HTTP request or data payload that triggers the quadratic parsing behavior. Since XML is commonly used in enterprise environments for configuration files, web services (SOAP), and document storage, the potential blast radius is substantial. Systems that do not implement strict input validation or size limits on incoming XML payloads are particularly susceptible to this form of algorithmic complexity attack.
Mitigation strategies must focus on both immediate patching and architectural improvements. The primary remediation step is to upgrade roxmltree to a version greater than 0.21.1, where the underlying parsing logic has been optimized to handle large attribute sets efficiently. For systems that cannot immediately update dependencies, defensive coding practices should be implemented at the application layer. This includes enforcing strict limits on the number of attributes allowed per XML element and validating namespace declarations before processing. Additionally, implementing timeout mechanisms for parser operations can prevent a single malicious request from monopolizing server resources indefinitely. Organizations should also consider adopting input validation frameworks that enforce schema constraints or maximum depth and size policies to preemptively filter out potentially abusive payloads before they reach the vulnerable parsing engine.