CVE-2026-114141 in toml-node
Summary
by MITRE • 10/21/2026
toml-node is a TOML parser for Node.js and the browser. Prior to 5.0.1, the toml.parse() compiler's addTableArray() function in lib/compiler.js rescans the complete assignedPaths and valueAssignments bookkeeping sets for every array-of-tables header. Distinct [[name]] paths are not pruned, so a document with many such headers causes quadratic synchronous work and can block the Node.js event loop, denying service to other operations in the process. This issue is fixed in version 5.0.1.
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Analysis
by VulDB Data Team • 10/21/2026
The vulnerability identified in toml-node versions prior to 5.0.1 represents a significant performance degradation flaw rooted in inefficient algorithmic design within the TOML parser's compiler logic. Specifically, the addTableArray() function located in lib/compiler.js is responsible for processing array-of-tables headers denoted by double bracket syntax such as [[name]]. For every instance of this header encountered during parsing, the function performs a full rescan of two internal bookkeeping data structures: assignedPaths and valueAssignments. These sets track previously processed paths and values to ensure correct hierarchical mapping within the TOML document structure. The core technical flaw lies in the failure to prune or optimize these scans based on distinct path identifiers. Instead of leveraging indexed lookups or incremental updates, the parser iterates through all existing entries for each new array element, resulting in a computational complexity that scales quadratically with respect to the number of table arrays present in the input document.
This quadratic synchronous work has severe operational implications for applications relying on Node.js environments where asynchronous event loop management is critical. Because the parsing operation blocks the main thread without yielding control back to the event loop, even moderately sized TOML documents containing numerous array-of-tables entries can cause substantial latency spikes. In a production environment, this blocking behavior effectively denies service to other concurrent operations such as handling network requests, processing user inputs, or executing background tasks. The impact is particularly acute in high-throughput scenarios where multiple clients may trigger parsing of complex configuration files simultaneously, leading to resource exhaustion and potential denial-of-service conditions for the entire application instance.
From a classification perspective, this vulnerability aligns with CWE-400: Uncontrolled Resource Consumption, as the parser fails to limit the computational resources consumed during input processing. It also relates to CWE-770: Allocation of Resources Without Limits or Throttling in the context of algorithmic complexity leading to performance degradation. In terms of attack vectors and tactics within the MITRE ATT&CK framework, this flaw could be exploited by an attacker providing a specially crafted TOML payload designed to maximize array-of-tables depth, thereby causing sustained CPU saturation and service disruption akin to CWE-787: Out-of-bounds Write if memory corruption were involved, though here the primary impact is availability through resource exhaustion.
Mitigation strategies primarily involve upgrading to version 5.0.1 or later of toml-node, where the underlying algorithm has been optimized to eliminate redundant rescans and properly manage path pruning. For applications unable to immediately update dependencies, implementing input validation to limit the depth or count of array-of-tables structures can provide a temporary defensive layer. Additionally, running TOML parsing operations within worker threads or isolated contexts can help isolate the impact on the main event loop, ensuring that other critical services remain responsive even if one parser instance experiences performance degradation due to complex inputs.